Background

Adnexal torsion is a rare cause of acute abdominal pain and diagnosis can be challenging because the presentation is often characterised by non-specific symptoms. It requires a high clinical suspicion for prompt diagnosis in order to save the adnexal organs.

Case report

A 32-year-old primiparous woman presented at 17 weeks with sudden onset of right iliac fossa pain that woke her from sleep. She described the pain as severe and constant, sharp in character, radiating down to her right groin and associated with nausea and vomiting. The patient did not have any vaginal discharge, bleeding or contractions. There was no other medical, surgical or gynaecological history of note. The pregnancy was naturally conceived with a normal antenatal course. Imaging to date had been unremarkable.

On examination, the patient was distressed, but afebrile and haemodynamically stable. She had right lower quadrant tenderness, with a palpable mass. Pelvic ultrasound reported right adnexal 75x42x34mm ovoid heterogeneous mass with no internal vascularity that appeared to be separate from the uterus. Blood flow to the right ovary could not be demonstrated. The fetal examination was normal.

Acute appendicitis was a differential diagnosis, but seemed unlikely. Adnexal torsion, although considered, was not convincing. The patient was admitted for analgesia and observation. On the following day, her abdominal pain remained localised in the right iliac fossa and seemed to improve. Bedside ultrasound was performed by the obstetrics and gynaecology team and suggested a dermoid cyst. With adequate analgesia, the patient remained comfortable and the inflammatory markers remained normal.

On the third day, her pain worsened with analgesia providing little relief. By this time, significant tenderness in the right iliac fossa with guarding was found. The C-reactive protein became elevated to 76mg/L. A decision was made for laparoscopy that revealed a 15cm necrotic tubo-ovarian mass with fallopian tube torsion. Detorsion did not return normal colour to the ovary or fallopian tube, so right salpingo-oophrectomy was performed. There were no postoperative complications or signs of preterm labour. Histology revealed tubo-ovarian torsion secondary to a benign dermoid cyst.

Pre-operative serum tumour markers CA 19-9 and CA 125 returned elevated readings at 497.4 and 70.5, respectively. Of note, spontaneous labour occurred at 40+8 weeks gestation and delivery was by caesarean section for prolonged second stage.

Discussion

Adnexal torsion accounts for about three per cent of gynaecological emergencies and is usually caused by the total or partial rotation of the ovary and the fallopian tube on its vascular pedicle.³ It can occur in all ages, but is more common during the reproductive years⁴ because of the development of a corpus luteal cyst during the menstrual cycle.³ It is a rare cause of abdominal pain in pregnancy, with an incidence of five per 10 000 pregnancies.⁵

 

Factors that predispose to adnexal torsion include tubal congenital or acquired anomalies, such as hydrosalpinx and tubo-ovarian masses.⁶ It may be associated with stimulation during fertility treatment, most notably IVF.⁵ An average 50–80 per cent of cases are associated with an ovarian tumour, typically benign, or with a large heavy cyst.³ When it occurs during pregnancy, torsion is common in the second and early third trimester and necrosis may precipitate peritonitis with preterm labour.^2,5,6 The commonest presenting symptom is lower quadrant pain, with non-specific symptoms such as nausea, vomiting and fever. The pain is typically sudden in onset and may be constant or paroxysmal, radiating to the thigh or groin.⁶ Torsion is more common on the right side, presumably owing to the sigmoid colon, which makes adnexal movement less likely on the left.⁴

No specific laboratory tests are helpful in the evaluation of a patient for suspected adnexal torsion in pregnancy.3 A raised white cell count is a non-specific finding and unreliable indicator of torsion. Imaging usually reveals an enlarged displaced ovary or adnexal mass, sometimes with evidence of haemorrhage and free fluid.³ Doppler flow studies are commonly equivocal³ and the absence of adnexal blood flow has a poor negative predictive value.²

Management of adnexal torsion in pregnancy is controversial owing to the associated risks.⁵ Laparoscopy during pregnancy has an increased risk of injury to the uterus and possibly pregnancy loss.⁸ The safest time to perform laparoscopic surgery in pregnancy is usually the second trimester, and surgery prior to the third trimester has the least risk of premature delivery.⁹ However, it remains unclear whether preterm labour associated with laparoscopic surgery in pregnancy is secondary to the underlying pathology or surgery itself.⁹

Acknowledgements

Thank you to Dr Julienne Grace who provided the histological examination of the lesion and Dr Rajiv Rattan who provided the pelvic ultrasound examination.

Consent

Written informed consent to publish this case report and images was obtained from the patient.