Percutaneouse ultrasound‐guided needle aspiration for management of breast abscesses – a review

Abstract Breast abscesses are still a common cause of morbidity among lactational females. Over the years, there has been an increase in the incidence of non‐lactational breast abscesses and a decrease in lactational breast abscesses. The management could be the use of the conventional method of surgical incision and drainage or the newer techniques of needle aspiration or suction drain or catheter in addition to the administration of antibiotics. The use of needle aspiration as the minimal‐invasive conservative technique is generally recommended for abscesses less than 3–5 cm in diameter. However, recent studies have compared the two methods for abscesses larger than 3 cm and among patients with risk factors for breast abscesses. We aim to present the clinical evidence showing the comparison between needle aspiration and incision and drainage for breast abscesses irrespective of the size of the abscesses. There is a lack of comparative information on the two treatment modalities for breast abscesses larger than 3 cm in diameter; however, needle aspiration is being tried because of its advantages like cosmetic preference, short hospital stay and healing time, and no stoppage of breastfeeding.


Introduction
Breast abscesses are one of the common causes of morbidity and interruption of breastfeeding among lactating women. [1][2][3] Approximately 0.4% of lactating women develop breast abscesses, and 3%-11% of women with mastitis may develop lactational breast abscesses. [4][5][6][7][8] Although the incidence of breast abscesses is low and is further decreasing in developed countries, these are still common causes of morbidity among women in developing countries. [9][10][11] The incidence of lactational breast abscesses seems to be decreasing, with a corresponding increase in the incidence of non-lactational abscesses. 10,12 Breast abscesses are most commonly caused by infections around the nipple due to biting by the child during feeding; bacterial colonisation due to improper nursing techniques, milk stasis, lactational breast inflammation, lack of proper hygiene and poor economic living, and delay in getting appropriate treatment. [1][2][3]12 Emergency treatment of breast abscesses might be required to restore normal feeding among lactational females and also to avoid the onset of complications. 1 The traditional management of breast abscesses included surgical incision and drainage (I&D); however, over time, aspiration with a needle or catheter drainage or suction drainage, or vacuum-assisted biopsy has replaced I&D, especially for breast abscesses smaller than 3 cm in diameter. [2][3][4][14][15][16][17] One of the initial comparator clinical studies comparing needle aspiration (NA) with I&D was published more than 25 years ago. 18 In the early years of this century, the emergency medical treatment guidelines for breast abscesses concluded that NA might be considered an effective first-line treatment in small breast abscesses. 19 However, there are lack of guidelines and algorithms for the management of breast abscesses for larger sizes. Additionally, the frontline healthcare workers are not fully trained in the protocols for allocating the patients into different treatment groups. 3 Both Ultrasound (US)-guided NA and I&D have been compared in various clinical studies and reviews. 8,[20][21][22] Management with NA is associated with a lower incidence of recurrence, low cost, and better cosmetic results, especially for abscesses <3 cm in diameter. 9,15,20,21 However, repeated aspirations and the large size of the breast abscess have been considered possible limiting factors. However, I&D is the traditional, invasive, and frequently used method for larger breast abscesses; it requires the use of general anaesthesia, the healing time is prolonged, regular dressings are required, restoration of breastfeeding is difficult, patients are unsatisfied with cosmetic outcomes as there is a high chance of wound granulation, there is a risk of rupture and recurrence of breast abscesses (10%-38%), and lastly, the increased cost is a financial burden on the patient. 1,9,13 Although the comparative studies and reviews have shown the benefits of NA compared to I&D for small (<3 cm in diameter) abscesses, there is a need to compare the management techniques, especially for larger breast abscesses, and to help formulate a management algorithm according to the presentation of breast abscesses. 8,20,21 We aimed to evaluate the currently available clinical evidence for the management of breast abscesses of different sizes and identify the limitations and strengths of these clinical studies for their future use in formulating treatment algorithms.

Characteristic features of breast abscesses
Lactational breast abscesses are generally located in the peripheral breast, and these are commonly reported among women having their first pregnancy, and generally occur in the second or third decade, while the nonlactational breast abscesses are mainly of sub-areolar type and generally occur toward the end of the reproductive years. 1,2,7,10,11,14,21,23,24 The most common causative organism is Staphylococcus aureus; however, Methicillin-Resistant Staphylococcus aureus (MRSA) is also increasing the disease burden, followed by Staphylococci epidermidis and Streptococcus. 1,[6][7][8]10,14,23,25 The most common site of breast abscesses is the upper outer quadrant, and some studies have shown a higher occurrence in the left breasts. 1,7,14,23 As mothers with cracked or sore nipples usually avoid breastfeeding from the affected side, there is a high risk of milk stasis, which further becomes another cause of breast infection. In addition to the signs of mastitis, like pain, warmth, redness of breasts, asymmetry of breasts, and difficulty in feeding, a fluctuant mass may also be present in patients with breast abscesses. 13,16,24 Non-lactational breast abscesses often have a chronic course and have a higher risk of developing into fistulas. 21 Both lactational and non-lactational breast abscesses generally need to be drained or aspirated.

Management of breast abscesses
The general measures include using analgesics, antibiotics, breast support, breast emptying (through pumping or nursing), and continuation of breastfeeding among lactating females. 6,8,12,14 Patients are generally instructed to continue breastfeeding from the unaffected breast, and the affected breast is routinely emptied with pumps. 14 US should be performed to identify the location and pockets of the abscess. The specific measures include the drainage or aspiration of the abscesses, which can be either by the NA technique (performed with or without US guidance) or the I&D of the abscess. 6 A patient is considered clinically recovered when no fever, no breast tenderness, or erythema is present.

Needle aspiration
Needle aspiration can be performed with or without US guidance. US-guided aspiration assists in locating the breast abscesses, and in needle positioning and thus enables visualisation of loculi and the adequacy of drainage. 8,9,14 After local anaesthesia, the needle is inserted (can be in the range of 14-18 G, and a 20 mL syringe), and the pus is drained with syringes. 9,24 The aspiration procedure is carried out until no further pus can be aspirated, and then the aspiration is repeated daily or on alternate days for the coming days. 8,9 If the abscess does not resolve after 5 aspirations, then it is considered a case of treatment failure, and another treatment modality is planned. 24
We used MEDLINE, Google Scholar, and The Cochrane Library as sources for evidence. Additional studies were searched using the reference lists from the clinical trials and reviews. The details of the clinical studies can be found in Table 1.

Clinical evidence Outcome measures
The reviewed clinical studies have included success rates, mean healing time and effect of breastfeeding, and cosmetic effects as the major outcome measures. Other outcome measures include the time taken for procedure and hospital stay, post-intervention symptoms, the incidence of complications, and cost analysis.

Success rate
The success rate (absence of symptoms and resolution of pus) has been widely used as an outcome measure in most of the clinical studies. Complete resolution of the abscess was considered a successful treatment with NA. 14 Most of studies have reported higher success rate with US guided procedure (Table 1). In one of the recent landmark clinical trials by Colin et al., 24 US-guided percutaneous drainage included NA and/or use of pigtail catheter. Colin et al. found that 92% (37/40) of lactational abscesses larger than 5 cm were successfully treated with US-guided procedure as a first-line treatment, and none of the cases needed any surgery. The number of percutaneous NA procedures per abscess ranged from 1 to 6 in the study. 24 Additionally, abscesses of >3 cm and advanced abscesses in a pre-fistula stage were also successfully treated with one or serial aspirations. 24 Retrospective analysis by Giess et al. 26 shows that there was no statistically significant difference in the success of the treatment based on the abscess size (Fisher's exact test, P = 0.727). Approx. 72.2% of abscesses among lactating and pregnant women and only 39.1% of the abscesses among non-lactating and nonpregnant females responded to NA treatment (Fisher's exact test, P = 0.058). 26 Similar results were reported by Karvande et al., as a success rate of 86.6% was achieved in the NA group. The mean size of breast abscesses (5.58 cm) in the NA group was significantly larger than in the I&D group (P = 0.028). 1 Karvande et al. 1 also reported that US-guided NA has great value even in the treatment of breast abscesses with large volumes as approx. 77% of the patients were successfully treated with two aspirations. Another study of US-guided NA by Kielar et al. 16 showed that 21 out of 22 cases healed without complications, and the patients could breastfeed and there was no milk retention. Fardhus et al. observed an 88% success rate in the US-guided NA group and Rigourd et al. reported that 64.3% patients were managed with one inspiration, and the rest needed two (28.6%) or three (3.6%) punctures. 23,27 Additionally, there was no significant difference in the mean amount of pus drained and the diameter of the abscesses. 22,26 Suthar et al. 36 have reported an 82.86% success rate in the US-guided NA group. Chandika et al. 9 mention 93.1% as a success rate as only 6.9% of patients were re-aspirated, and no abscess was converted to the I&D group from the NA group. Sikandar et al. 13 report that 5% of patients from the NA group needed re-aspiration, 5% had to undergo I&D, and the rest of the 90% had successful treatment. Eryilmaz et al. reported that a mean of 3.5 (range 1-5) aspirations were performed in the NA group; 45% of patients required multiple aspirations, and I&D technique was used among 41% of patients after failure with NA technique. 14 Although Eryilmaz et al. 14 had conducted NA without US guidance, NA was successful among all patients with abscess diameter smaller than 5 cm; and it was also successful among 25% of patients with abscesses larger than 5 cm in diameter (P < 0.05). Randhawa et al. 2 found that both NA and I&D techniques led to successful results (P = 0.046) among both lactating and nonlactating female patients. Ding et al. 25 reported no significant difference between the methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) groups regarding abscess sites, number, and size of abscess cavities. Although all patients were treated with US-guided aspiration, and no comparison could be drawn with I&D, the results show that all the abscesses were treated successfully, irrespective of the size of the abscesses. 25 Sushel et al. 35 show that the number of aspirations increases with the increase in the size of the abscesses. Abscess sizes in all non-responders were >5 cm in diameter. 35 Berna-Serna et al. 10 found that 86.4% of the patients who underwent US-guided NA had been relieved from acute symptoms within 24-48 hours of the drainage. Elagili et al. 28 reported a success rate of 83.3% with NA and 13.3% were referred for surgical I&D. Similarly, Singh et al. 37 also mention that there was no treatment failure with NA for abscesses of 4 cm diameter, whereas 7 out of 11 abscesses with sizes >4 cm I&D had to be performed after failure with NA.
Other studies have shown lower success rates with NA (Table 1), as Saeed et al. 33 have reported a failure rate of 20% in the NA group and no failure in the I&D group. Egbe et al. 4 found that 44% of participants from the NA group (without US-guidance) were aspirated three times, and in 24%-28% of patients, the abscesses resolved in 8-9 days. Singh et al. 37 found no treatment failure in cases with abscesses of 4 cm, and 64% of those abscesses larger than 4 cm had a treatment failure. Mean number of aspirations required for all patients was 3, (ranging from 1-to 5). 37 The success rate was 78% with NA, 16%    needed I&D, and the remaining 6% had a recurrence of abscesses. 37

Mean healing time
Healing time for I&D has been defined as the time from incision and drainage to wound closure. 14 Several clinical studies have reported significant shorter mean healing time with NA compared to I&D (Table 1) 1,14,33 However, the comparison will be biased as they did not include 41% of the patients in analysis from the NA group who had treatment failure. 14 Similarly, Suthar et al. 36 found the mean healing time to be significantly shorter; however, they had excluded the treatment failures from the analysis. Dener et al. 7 also showed a shorter mean healing time in the US-guided NA group (8.6 days, range 5-12 days) compared to the I&D group (10 days, range 6-15 days, P = 0.22).
Chandika et al. did not find any significant difference in the mean healing rate, as 65.5% from the US-guided-NA group and 58.1% from the I&D group were healed by the 3rd visit. 9 Clinical study by Egbe et al. 4 report 6-10 days as the resolution time with NA without US guidance respectively. Fardhus et al. 23 also showed that mean healing time was significantly shorter in the NA group (4.27 days) compared to the I&D group (7.60 days).

Breastfeeding
It is crucial to continue breastfeeding for the mother and infant's health as milk stasis is a risk factor for further development of mastitis and breast abscesses. 13 Additionally, separating the baby from the mother has a psychological effect on the mother. 37 Breastfeeding should be resumed after aspiration and can be continued even with a drain in place with proper precautions. Although there are concerns about the risk of infection to the infants, only a few clinical reports have suggested transmission of infections to the infants. 39 However, Most of the clinical studies report uninterrupted breastfeeding in NA with or without US-guided procedure, 13,24,4 in addition to studies that compared the NA group with the I&D group 27,29,31,32 (Table 1). Sikandar et al. reported that a significantly lower number of patients had cessation of breastfeeding in the NA group than in the I&D group (P < 0.05). About 66% of patients continued breastfeeding during treatment with NA in Sikander et al. study. 13 Colin et al. 24 have also shown that 91% of women continued breastfeeding when patients underwent NA or NA and pigtail catheter drainage for breast abscesses. Egbe et al. 4 recorded continuation of breastfeeding among 76% of the patients after NA without US guidance. Even early (within 24 hours) restoration of breastfeeding is also significantly more in the US-guided NA group compared to the I&D group (P = 0.011). 29 Time taken for procedure and hospital stay The shorter hospital stay decreases the separation time between the mother and the child. The use of general anaesthesia for I&D compared to the use of local anaesthesia for NA helps in decreasing the hospital stay.
All the clinical studies measuring the duration of the procedure and hospital stay show a lesser time during NA procedures and, shorter hospital stays in the NA group (Table 1). 1,11,23,32 Cosmetic outcomes There was a significant difference in the level of satisfaction among patients from the NA group and the I&D group (Table 1). 1,23,33 A clinical study compared the scars with the Manchester scar scale, and the NA group had alower mean score (P = 0.0008) than the I&D group. 38 Patients of the NA group have reported high satisfaction with the aesthetic effect of the treatment, and after three months there were no visible scars or breast deformations. 1,14,16,32,33,38 Post-intervention symptoms The duration of pain and fever was less, varying from significant to non-significant levels in the NA group (Table 1). 1,11,23 Patients undergoing NA did not have to be separated from their babies thus preventing any psychological disturbances among the lactating females. 37 Residual abscess was higher in the NA group compared to the I&D group, whereas incomplete wound healing was more prevalent in the I&D group in an analysis by Patil and Vanger. 32 Post-procedural complications Complications in either of the techniques include incomplete clearance, recurrence, fistula formation, and milk suppression.
Failure of the procedure Failure was seen in 13.3% of patients in the NA group and in 3% in the I&D group in the study by Karvande et al. 1

Fistula formation
Reviews and clinical studies have shown that the risk of fistula formation is lower with US-guided NA. 6,8,29 A systematic review of milk fistula among lactating mothers shows that milk fistulae are more frequent following I&D than after needle aspirations. 40 Naeem et al. 31 have also reported a higher number of complications (milk fistula) in the I&D group compared to the NA group.

Cost analysis
Although it is well documented that I&D is costlier than NA, only a few studies have included the financial aspect and found that NA is cost-effective compared to the I&D method for breast abscesses. 9

Discussion
Review of clinical outcomes with US-guided NA and I&D procedures shows that the former technique is the first choice for breast abscesses <3 cm in diameter. Additionally, recent studies favour the use of US guided-NA for abscesses >5 cm in diameter as well. [23][24][25]27 NA with or without US guidance has shown better success rates and cosmetic outcomes, shorter mean healing times and duration of procedures, among abscesses >5 cm in diameter as well. [23][24][25]27 Early restoration of breastfeeding or non-interruption of breastfeeding is significantly better in the NA group compared to I&D groups in all studies. 6,11,21 US-guided NA has been successful in both MSSA or MRSA-infected breast abscesses. 25 I&D is especially considered among cases of recurrences after NA or if NA is not successful because of thick pus or the large size of the abscess. 7 Review of the available studies also shows that the patients could continue breastfeeding during NA percutaneous treatment. While the patients undergoing I&D need regular dressings, there is a cessation of breastfeeding, and there is a high risk of fistula formation and post-operative scarring is also observed. 6,8,11 Breast abscesses have been commonly located in the upper outer quadrant and in the left breasts. 9,14,23 Some clinical studies have also reported the risk (or predisposing) factors for the occurrence of breast abscesses. Lactation, cracked nipples, milk stasis, primiparous females, first 12 weeks in the post-partum period, second-trimester pregnancy, advanced maternal age, recent breast intervention (biopsy or nipple piercing or lumpectomy), subareolar abscess, smoking, immunocompromised state, diabetes, duration of symptoms before treatment, and increasing age have been suggested as the possible risk factors for occurrence and reoccurrence of breast abscesses. 4,7,12,26,28 Failure of treatment has been linked with smoking, the presence of nipple rings, multiloculation, and abscess size. 12,28 Additionally, the review brings forth the limitations and strengths of the two procedures. Recent studies highlight the need to stratify the patients according to baseline features like the size of the abscess and viscosity of the pus before deciding the treatment modality. The benefits and risks of NA and I&D should be weighed before opting for one of the two treatment options. The use of NA for abscesses larger than >5 cm may require a higher number of re-aspirations; however, the duration of hospital stay, time for the procedure, effect on breastfeeding, cosmetic outcomes, and the cost are all favourable for the NA method compared to the I&D technique (Table 1). 1,9,11,23,24,26 The use of US guidance for diagnosis and during the procedure can help stratify the patients for selecting the treatment method. Irrigation with saline solution and local use of antibiotics helps in decreasing the viscosity of the pus and high concentrations of antibiotics act directly on the microorganisms. 4 Aspiration of the breast abscess can be successfully done as the initial mode of management in the treatment, but I&D may remain the final resort for non-responders.
Another interesting aspect of the review includes the update about the newer techniques and management strategies for breast abscesses. Vacuum-assisted biopsy (VAB), or Mammotome, has been used in cases of failure with NA or as a substitute for NA. 24,41 Some authors have reported that a Mammotome may be used along with NA if the abscess is too viscous or it is loculated. 42 Use of catheters for larger breast abscesses can help to decrease the failure rate and hospital stay. 10,15,43 Other studies have suggested open drainage followed by primary closure with negative suction drain placement as a safe and better alternative to the standard I&D as there is reduced post-operative pain, shorter hospital stay, and fewer dressings required. 44 Also, aspiration of the breast abscess through a wide bore cannula can be done, although this technique might require multiple aspirations. No mode of anaesthesia is required, and it can be done on an outpatient department basis. Apart from the newer techniques, proper stratification of patients according to the size of breast abscess, and viscosity of the pus while choosing the management technique for breast abscesses may also improve the outcomes. 24 The descriptive review has some limitations and strengths. Although decades have passed since the introduction of US-guided NA for breast abscesses, comparative analysis of the treatment techniques is marred by the limiting factors of the clinical studies. First and foremost, most of the clinical studies have not distinguished lactational and non-lactational patients as two separate groups. 11 Most of the clinical studies are retrospective, or open labelled, or single-arm clinical studies with small sample size. 10,12,24,25 Additionally, there are differences in the procedures adopted in the clinical trials, as some have used both NA and pigtail catheter, and some used NA with or without US-guidance. 12,24 There were no inclusion criteria concerning abscess size and duration of breast abscesses in most of the clinical studies. Many clinical studies had not included breast abscesses with a larger diameter. The strengths include a wider data search without any restriction of time or language. We tried to include clinical studies without restricting language, patient population, and outcome analysis. Overall, the currently available clinical evidence is insufficient to compare the available treatment options for breast abscesses. Thus, we require data from large sample-sized real-world studies or randomised controlled clinical trials.
Future directions: There is a need to formulate protocols for treating breast abscesses (both lactational and non-lactational), according to the presence of various risk factors and comorbid conditions. The algorithm should include the status of all procedures like suction and drainage, and use of pigtail catheter in addition to the commonly used NA and I&D. This should also include the number of recommended reaspirations before considering the failure of treatment with NA. Additionally, there is a need to establish the benefits of local infiltration of antibiotics compared to oral administration. There is also a need to compare the advantages and disadvantages of US-guided percutaneous catheter drainage treatment modality compared to USguided NA and I&D. The current clinical evidence is also deficient in the preference for the US guidance or palpation method. Maintenance of disease and treatment registries in hospitals can help generate clinical evidence.

Conclusions
The available clinical studies suggest that the percutaneous US-guided NA, a minimally invasive technique, is associated with a shorter mean healing time and mean duration of hospital stay, higher success rate, acceptable cosmetic results, minimal effects on breastfeeding, acceptable patient satisfaction, and emotional stability among patients with breast abscesses. The review highlights the need to generate comparative data of NA and I&D as treatment modalities for breast abscesses more than 5 cm in diameter. Multi-centred randomised clinical trials with a larger sample size can help in generating comparative results.