Pelvic abscess following microwave endometrial ablation
Article first published online: 13 SEP 2004
BJOG: An International Journal of Obstetrics & Gynaecology
Volume 112, Issue 1, pages 118–119, January 2005
How to Cite
Das, S., Kirwan, J., Drakeley, A.J. and Kingsland, C.R. (2005), Pelvic abscess following microwave endometrial ablation. BJOG: An International Journal of Obstetrics & Gynaecology, 112: 118–119. doi: 10.1111/j.1471-0528.2004.00284.x
- Issue published online: 13 SEP 2004
- Article first published online: 13 SEP 2004
A 44 year old woman presented with severe left-sided lower abdominal pain three days after a microwave endometrial ablation for menorrhagia. The pain was described as sharp, worsened with movement and associated with vomiting. She had not opened bowels since the operation. It was severe enough to require opiate analgesia. She had undergone a microwave endometrial ablation procedure three years previously for treatment of menorrhagia. However, over the last eight months, the symptoms had returned and she requested a second microwave endometrial ablation. She had a twin pregnancy following IVF treatment 11 years ago. The twins had been delivered by caesarean section. She was also known to have pelvic endometriosis.
The microwave endometrial ablation procedure was preceded by saline hysteroscopy that revealed a normal size, anteverted uterus with a regular endometrial cavity. The saline was then aspirated from the endometrial cavity. An uneventful microwave endometrial ablation was then performed. The treatment lasted 2½ minutes and the entire cavity was ablated.
On admission, the patient was febrile and tachycardic. Abdominal examination revealed tenderness over the left iliac fossa but was not associated with guarding or rebound. Bowel sounds were present and normal.
A full blood count revealed an elevated white cell count of 15.1 × 109/L with a predominance of neutrophils, C-reactive protein was raised at 374 mg/L (normal <5 mg/L). Abdominal and chest X-ray did not show any evidence of bowel perforation. A working diagnosis of endometritis was made, and a broad-spectrum antibiotic commenced. Her symptoms initially settled with this treatment. Transabdominal ultrasound scan showed a 6-cm mass of mixed heterogeneity in the left iliac fossa. CA125 was found to be mildly elevated at 44 IU/L (normal <25 IU/L).
In view of these findings, laparotomy was performed via a midline incision. On the left side, a pelvic abscess of approximate size 7 × 10 cm was identified. The abscess extended up the left pelvic side wall beneath the sigmoid mesentery and inferiorly to the uterus. Although the sigmoid colon itself was inflamed, the serosa was intact with no evidence of thermal injury. The uterine serosa showed signs of inflammation without any evidence of thermal injury or perforation. The left tube and ovary could not be visualised. The right ovary had an endometrioma of approximately 4 cm, and was adherent to the pelvic wall on that side. The Pouch of Douglas was obliterated by adhesions.
Following surgical drainage, treatment with intravenous metronidazole, 500 mg 8 hourly, and ciprofloxacin, 500 mg 8 hourly, was followed by oral antibiotics for two weeks. Microbiological culture from the abscess revealed growth of lactose fermenting coliforms and mixed anaerobes and confirmed sensitivity to the prescribed antibiotics. The patient made a good recovery and was discharged home on the seventh post-operative day.
The woman was readmitted 10 days later with a recurrence of symptoms. Full blood count continued to show raised white cell count with predominant neutrophilia and a raised C-reactive protein (181 mg/L). A transabdominal ultrasound scan revealed free fluid in the pelvis with a mixed echogenic area adjacent to the right ovary. Ultrasound guided aspiration of this collection confirmed blood clots. The woman made a full recovery following treatment with antibiotics (selected after sensitivity testing). The full blood count and C-reactive protein had returned to normal at review two weeks later.
Microwave endometrial ablation was introduced as a second-generation ablation technique by Sharp et al.1 and is universally regarded as simpler, quicker, safer and equally successful for the treatment of menorrhagia due to dysfunctional uterine bleeding.2 However, only one randomised controlled trial has compared microwave endometrial ablation with transcervical endometrial resection. This trial did not show any significant difference in the outcome between the two groups regarding complications, post-operative analgesia and duration of surgery among other parameters.3
NICE guidelines on interventional procedures recommend careful use of all thermal endometrial ablation techniques in the presence of small, thin-walled uteri and/or a history of pelvic infections where bowel adhesions are likely to be present. In the absence of guidelines specifically relating to use of second-generation ablation techniques, these precautions could be extended to include microwave endometrial ablation procedure (guidelines currently under preparation by NICE).
The use of microwave endometrial ablation is contraindicated in women who have previously undergone surgical endometrial ablation/resection techniques or uterine surgery resulting in a uterine wall thickness of less than 10 mm. The use of microwave endometrial ablation for re-ablation has not been previously reported. Rollerball, transcervical endometrial resection and other thermal balloon techniques, however, have been used for re-ablation of the endometrial cavity. In a series of 1400 microwave endometrial ablation procedures, Parkin4 reported a single case of small bowel perforation in a patient who had had two previous caesarean sections. More recently, a second case has been reported in a patient who had a history of previous laparotomy and laparoscopies for the diagnosis and treatment of endometriosis.5 Other published case series have reported the occurrence of other minor complications, mainly blunt perforation of the uterus with cervical dilators (0.2–0.5%), burns to the cervix or vagina (0.1%), vaginal bleeding or discharge (74–87%) and pain (60–75%).2 We are not aware of any published data reporting the development of an acute pelvic abscess following microwave endometrial ablation.
Ovarian endometriomas may become infected either by direct inoculation, ascending infection through the vagina and cervix, haematogenous spread or direct spread from the colonic wall and lymphatics. Blood retained in endometriotic cysts acts as a medium for bacterial growth, thus making them susceptible to infection and the development of an abscess.
The pathogenesis of the pelvic abscess in this case could be attributed to infection of a pre-existing endometrioma, pelvic inflammatory disease or infection of a traumatic haematoma secondary to the procedure. As our patient is a middle-aged woman, in a stable relationship without any previous history of pelvic inflammatory disease, acute pelvic inflammatory disease is unlikely. A previous history of endometriosis and presence of an endometrioma at laparotomy favour infection of a pre-existing endometrioma as the likely cause of the pelvic abscess. The presence of coliforms and mixed anaerobes in the abscess also supports the ascending route of infection during the operative procedure.4
This case highlights the possible complication from use of microwave endometrial ablation as a second procedure where the uniformity and thickness of the endometrium may be reduced. In addition, adhesions from previous surgery and endometriosis also predispose to the occurrence of serious complications (i.e. bowel injury4,5 and possibly pelvic abscess), as in this case.
The presence of endometriosis, especially with an endometrioma, should be recognised as a risk factor for the development of pelvic abscess following endometrial destructive techniques. Although repeat microwave endometrial ablation is not contraindicated, pretreatment ultrasound scan is mandatory to confirm that the uterine wall thickness is at least 10 mm, and to rule out associated pelvic pathology such as endometriotic cysts or hydrosalpinx. Despite being a low risk gynaecological procedure, prophylactic intravenous administration of broad-spectrum antibiotics at microwave endometrial ablation in women with a history of endometriosis or pelvic inflammatory disease may minimise the risk of pelvic abscess.
- 2NICE guidelines. Available: http://www.nice.org.uk/ip065 overview.
- 4Parkin DE for the MEATM Users' Group. Microwave endometrial ablation (MEATM): a safe technique? Complication data from a prospective series of 1400 cases. Gynaecol Endosc 2000;9(6):385–388.DOI: 10.1046/j.1365-2508.2000.00381.x
Accepted 25 March 2004