Torsion of normal adnexa in postmenarcheal women: can ultrasound indicate an ischemic process?

Authors

  • N. Smorgick,

    1. Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Zerifin, Israel, affiliated with the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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  • R. Maymon,

    Corresponding author
    1. Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Zerifin, Israel, affiliated with the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
    • Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Zerifin, 70300, Israel
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  • S. Mendelovic,

    1. Department of Pathology, Assaf Harofeh Medical Center, Zerifin, Israel, affiliated with the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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  • A. Herman,

    1. Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Zerifin, Israel, affiliated with the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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  • M. Pansky

    1. Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Zerifin, Israel, affiliated with the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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Abstract

Objective

Torsion of normal adnexa is a rare event involving steadily increasing congestion and ischemia of the ovary. We investigated whether this process can be characterized by sonographic features.

Methods

Twelve menstrually cycling women with 14 separate episodes of laparoscopic-proven torsion of normal adnexa were identified retrospectively, and the results of their preoperative gray-scale ultrasound examinations and Doppler flow evaluations were analyzed. The cases were classified into ‘short-term’ (< 24 h; range, 3–24 h) and ‘prolonged’ (> 24 h; range, 1–10 days) duration of torsion according to the reported period of abdominal pain before admission. Absence of any additional adnexal pathology was confirmed by both intraoperative inspection and postoperative follow-up ultrasound examinations.

Results

The median age of the cohort was 24.0 (interquartile range (IQR), 20.5–28.7) years, and parity ranged from 0 to 3. All affected ovaries were significantly enlarged compared with non-affected ones (median cross-sectional area, 18.1 (IQR, 12.4–26.4) cm2 vs. 4.3 (IQR, 2.9–6.2) cm2, P < 0.01). We could distinguish two distinct sonographic patterns of torted ovaries: there were numerous small peripheral follicles in the ovarian parenchyma in nine cases, and there was a solid-appearing mass with hypo- and hyperechogenic foci in five cases. Comparison of the ultrasound images of patients with short-term vs. long-term abdominal pain revealed that the solid-appearing ovary was more common in the latter group (0/6 vs. 5/8, P = 0.03), while there was no significant difference between groups in the presence of free pelvic fluid or median ovarian cross-sectional area. Intraovarian blood flow was diminished or absent in five of the eight patients in whom color Doppler imaging was performed.

Conclusions

Ultrasound images of twisted normal adnexa may vary according to the duration of the condition, reflecting the pathological series of events of increased ovarian congestion and necrosis. Recognition of the different sonographic features of twisted normal adnexa may assist in the correct diagnosis of these patients. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.

Introduction

Adnexal torsion accounts for approximately 3% of all gynecological emergencies and may be an important cause of abdominal pain1. The major imaging tool in the diagnosis of torsion is pelvic ultrasound, which is used to demonstrate ovarian masses and ovarian enlargement following ovarian stimulation (both conditions being a common underlying cause of adnexal torsion1, 2), and to rule out other causes of acute abdominal pain, such as ruptured ovarian cyst, tubo-ovarian abscess and acute appendicitis3. The role of sonography in the diagnosis of torsion of previously normal adnexa is considered as being more limited. This condition was believed to occur mainly in premenarcheal girls, possibly due to long or hypermobile ovarian ligaments4. However, we recently reported that torsion of the normal adnexa is not infrequent in postmenarcheal, non-pregnant patients, comprising up to 24% of cases of torsion in this age group5.

The sonographic findings of twisted normal adnexa appear to be subtle, the detection rate being 46–74%6, 7. Graif et al.6 described gray-scale transabdominal ultrasound examination of five young females (aged 4–15 years) with this condition. The affected ovaries were enlarged up to 28 times the normal ovarian volume, no associated ovarian masses or pathology were found, and multiple cystic structures were seen in the ovarian periphery. However, this case series was limited because of the relatively small number of cases, and because all torsion cases involved children or adolescents.

Adnexal torsion is an ischemic process that evolves over time. We hypothesized that the progression of ovarian ischemic insult may be reflected by sonographic findings. Accordingly, we investigated retrospectively ultrasound images of twisted normal adnexa, in a preselected series of menstrually cycling females with surgically proven torsion of normal adnexa, focusing on cases with supposed long-standing vs. short-term ovarian ischemia.

Methods

A computerized database search for cases of adnexal torsion which underwent surgery in our institution from January 2002 to June 2006 yielded 12 menstrually cycling women with torsion of normal adnexa, based on the collective data of clinical presentation, preoperative sonography, operative reports and pathological diagnosis (when available). Gravid women and patients undergoing ovulation-induction treatments as well as those with any additional ovarian pathology were excluded. All patients included in the current study were managed by laparoscopic surgery, either with conservative detorsion, or with salpingo-oophorectomy. As part of our departmental routine, the absence of any adnexal pathology in patients who underwent conservative detorsion was confirmed by a postoperative ultrasound examination conducted between 2 months and 2 years following surgery.

The preoperative ultrasound images and ultrasound examination reports of the study patients were analyzed retrospectively. The preoperative ultrasound examinations were performed with different ultrasound machines from various manufacturers, all equipped with a transvaginal probe (5–7.5-MHz, with a focal range of 6 cm from the transducer tip) and a transabdominal probe (3.5–5-MHz). The transabdominal examination was used mainly for virgins and was performed using the patient's full bladder as an acoustic window. Color Doppler flow examinations were performed in eight cases.

Because this was a retrospective study, only the pre-existing measurements of ovarian diameters that had been recorded in the patient's medical records were available. All patients had records of two ovarian diameters (long and short axes) for both ovaries, enabling us to calculate the ovarian cross-sectional area but not its volume.

All patients were admitted immediately upon presentation. For descriptive purposes, cases were classified according to the duration of abdominal pain (with or without nausea/vomiting) before admission, obtained retrospectively by a review of their medical records. The first group, defined as ‘short-term’ duration of symptoms, included cases whose onset of symptoms was < 24 (range, 3–24) h before admission. The complaints of the women in the group with ‘prolonged’ duration of symptoms began from > 24 h to 10 days prior to admission. The cut-off between the two groups was defined arbitrarily.

The Wilcoxon rank test, Mann–Whitney U-test, and the Fisher's exact test were used for statistical analysis. P < 0.05 was considered statistically significant.

This study was approved by the institutional review board.

Results

The study group included 12 menstrually cycling women with a median age of 24.0 (interquartile range (IQR), 20.5–28.7) years and a range in parity of 0–3. During the study period, 10 women had one episode of torsion, and the remaining two had two episodes, yielding 14 separate torsion events for analysis. The clinical presentation included abdominal pain in all cases, nausea or vomiting in 10 (78.6%) cases, and fever in three (21.4%) cases. All women had abdominal tenderness on palpation. Additionally, localized adnexal tenderness was elicited on either pelvic (in coital patients) or rectal (in virgin patients) examination in 11 (78.6%) cases. There was an elevated white blood cell count (>11 000 cell/mL) in three (21.4%) cases. The median time to operation from admission for the entire cohort was 12.1 (IQR, 6.1–15.3) h. At laparoscopy, torsion of a normal adnexa was confirmed in all cases, and involved the right adnexa in nine (64.3%) of them. Thirteen torsion episodes were managed conservatively by detorsion. One patient (aged 44 years) underwent salpingo-oophorectomy, and her pathological diagnosis was consistent with torsion of a normal ovary (i.e. hemorrhagic necrosis) (Figure 1).

Figure 1.

Photomicrograph of a twisted ovary showing areas of hemorrhage (H) and inclusion cysts (arrows) (hematoxylin–eosin stain).

The preoperative ultrasound examination was abnormal in all 14 cases. All the affected ovaries were significantly enlarged compared with the contralateral non-affected ovaries, with median cross-sectional areas of 18.1 (IQR, 12.4–26.4) cm2vs. 4.3 (IQR, 2.9–6.2) cm2 (P < 0.01). We could distinguish two different patterns of the twisted ovaries on B-mode sonograms. The most common pattern, found in nine (64.3%) cases, was of an enlarged ovary with numerous small peripheral follicles in its parenchyma (Figure 2 and Videoclip S1). The normal ovarian architecture. The been replaced by a solid-appearing mass with hypo- and hyperechogenic foci in the remaining five (35.7%) cases. Free pelvic fluid was present in 10 (71.4%) cases.

Figure 2.

Transvaginal ultrasound image of twisted normal adnexa in a 23-year-old woman. The ovary is enlarged and multiple small follicles are visible in its periphery.

A transabdominal ultrasound examination showing an enlarged twisted ovary compared with the normal one is presented in Videoclip S2, demonstrating the loss of the normal ovarian architecture. The pelvic laparoscopy of this patient is presented in Videoclip S3.

We attempted to correlate the sonographic findings with the duration of symptoms after classifying the cases into a short-term group (n = 6) and prolonged group (n = 8) (Table 1). Neither the ovarian cross-sectional areas nor the presence of free pelvic fluid were statistically different between the two groups, but the sonographic image of multiple small peripheral follicles in the ovarian parenchyma was significantly more common among patients with short-term duration of symptoms (P = 0.03).

Table 1. Sonographic features of 14 episodes* of torsion of normal adnexa, grouped according to duration of the patient's symptoms prior to admission
FeatureDuration of symptomsP
Short-term (< 24 h) (n = 6 episodes)Prolonged (24 h–10 days) (n = 8 episodes)
  • *

    Two patients each had two torsion events; the total number of patients was 12. IQR, interquartile range.

Gray-scale pattern of affected ovary (n (%))  0.03
 Multiple peripheral follicles6 (100)3 (37.5) 
 ‘Solid’-appearing ovary05 (62.5) 
Ovarian cross-sectional area (cm2, median (IQR))15.1 (13.1–19.3)21.8 (11.9–28.5)0.4
Presence of free pelvic fluid (n (%))3 (50)7 (87.5)0.2

Color Doppler flow examinations were performed in eight women and demonstrated absent or diminished intraovarian flow in five of them. On routine follow-up, the findings of all postoperative ultrasound examinations were consistent with normal ovaries.

Discussion

Adnexal torsion, defined as complete or partial rotation of the adnexa around the pedicle, causes several vascular events. First, the venous and lymphatic drainage systems are occluded, leading to ovarian congestion and to the accumulation of pelvic fluid. Next, the ovary undergoes hemorrhagic necrosis due to arterial occlusion. These are dynamic events and it is supposed that they evolve and increase over time. The current case series focused on patients with short-term versus prolonged duration of twisted normal adnexa and questioned whether these dynamic events have parallel ultrasound features. The sonographic features we investigated were ovarian enlargement, free pelvic fluid and the gray-scale sonographic appearance of the ovary. The first two signs, probably reflecting ovarian congestion, appear to have a high sensitivity (90–100%), but their specificity is supposedly low (exact data not reported)2, 7, 8. The third sign of torsion, the presence of small cystic structures in the periphery of the enlarged ovary, was described by Graif et al6, 7 in two case series comprising seven cases of twisted normal adnexa. They reported the specificity and positive predictive value of this sonographic sign to be 93% and 87.5%, respectively.

In this study, we identified several sonographic features that might help to distinguish between cases with a presumed short compared with a longer ischemic process. An acute torsion event causing mild ovarian congestion due to occluded venous flow may present sonographically as mild ovarian enlargement and scant free pelvic fluid. The ovarian architecture is probably still preserved, although the edema surrounding the follicles may be manifested on gray-scale ultrasound as multiple small follicles scattered in the ovarian periphery (as described previously by Graif et al.6). Conversely, in a prolonged torsion event, both the venous and the arterial blood flows may be compromised. The increasing ovarian congestion may present as even larger ovaries with more accumulated free pelvic fluid (albeit both findings were statistically non-significant in our study). At the same time, the ischemic process may disrupt the normal ovarian architecture, lending a ‘solid’ appearance to the ovary on gray-scale ultrasound. This last sign was indeed significantly more common in cases of prolonged torsion.

Impaired venous and/or arterial blood flow in the twisted ovarian pedicle (the whirlpool sign) was studied by Vijayaraghavan9. According to his experience with 21 cases of torsion (with various underlying ovarian tumors), the absence of venous blood flow with an intact arterial flow or the absence of both venous and arterial flows is predictive of a non-viable ovary. The different patterns of blood flow may also reflect short- or long-standing adnexal torsion and resulting ischemia, although this correlation was not studied directly. We could not confirm his results in our current study of women suffering from torsion of a normal adnexa.

Our case series had several limitations. The most obvious one is the reliance upon the retrospective data of a small number of patients, making it subject to bias. A prospective study could, however, be very difficult to set up due to the rarity of this event. Another limiting factor is that we were able to calculate only ovarian cross-sectional area rather than true ovarian volume, which is a more accurate measurement. In addition, the distinction between short-term and prolonged duration of torsion was made arbitrarily, partly because this subject has not been discussed in the relevant literature. This temporal distinction between the two types of torsion may have been further biased by different degrees of vascular occlusion, i.e. partial or complete9.

Taking into account the limitations of this study, we conclude that the sonographic appearance of the twisted normal adnexa is dynamic, reflecting the pathological series of events of increased ovarian congestion and necrosis as confirmed histopathologically (Figure 1). The data from this study and similar reports contribute to knowledge of ultrasound examination of patients with suspected torsion of normal adnexa, and serve to promote their correct diagnosis.

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