Postpartum ovarian vein thrombosis

Introduction

Postpartum ovarian vein thrombosis (POVT) is a rare pathology with an incidence estimated to 0.05–0.18% of pregnancies. It can cause serious complications such as sepsis, extension of the thrombus to the inferior vena cava in 9.5%, and pulmonary embolism in 9.5–13% [1], [2], [3], [4], [5]. Its first clinical description was made in 1956 in a 22-year-old patient who presented two days postpartum with right abdominal pain, vomiting and a tender palpable mass [6]. Although most commonly encountered in the postpartum period – with caesarean section and twin delivery identified as additional risk factors –, ovarian vein thrombosis (OVT) can also occur in the context of pelvic inflammatory disease, inflammatory bowel disease, pelvic surgery and malignancy [1]. Its diagnosis is challenging seeing that its clinical presentation mimics other, far more frequent, conditions. Here we report a case of POVT to illustrate this difficulty – potentially leading to erroneous management – and to underline the importance of considering POVT in the differential diagnosis of acute abdominal pain in the postpartum period.

Case presentation

A 26-year-old, healthy female presented to our emergency department four days after an uncomplicated vaginal delivery, with a one-day history of worsening right-sided lower abdominal pain. She was tachycardic (110 bpm) and febrile (38 °C) on presentation. She was oriented, her blood pressure was normal and the capillary refill time was less than 2 s. Physical examination revealed right iliac fossa tenderness with rebound pain and positive and Psoas test. Laboratory investigations demonstrated leukocytosis (14 × 10⁹/L) and a raised CRP (38 mg/L on admission, that rose to 190 mg/L in almost 24 h). Urine dip analysis was unremarkable and renal function was normal. Her venous lactate level was slightly raised at 2.2 mmol/L.

Following assessment by both the obstetric and surgical teams, appendicitis was felt to be the likely diagnosis in view of the overall presentation, although endometritis was also considered in the differential diagnosis in view of the patient’s recent postpartum. Ovarian torsion and ovarian cyst rupture were also mentioned in the differential but thought to be less likely in view of the septic clinical picture. Broad-spectrum intravenous antibiotics (cefuroxime 1.5 g and metronidazole 500 mg, both tds) were initiated. An abdominal-pelvic computed tomography (CT) scan was performed prior to proceeding with a laparoscopy for management of appendicitis. This investigation, however, showed no evidence of appendicitis but did raise the possibility of a right OVT, with an expanded right gonadal vein surrounded by perivascular inflammatory stranding (Figure 1A and B). A transabdominal ultrasound (US) confirmed the diagnosis by showing heterogeneous echogenic material in the right gonadal vein and no measurable venous flow within it (Figure 1C). In addition to antibiotics, the patient was initiated on therapeutic doses of low-molecular-weight heparin administered subcutaneously. Prognosis is favorable if treatment is promptly initiated [1].

Figure 1:

 Radiological appearances of postpartum ovarian vein thrombosis. (A) Coronal slice of a contrast enhanced abdominal-pelvic computed tomography (CT) scan. The medial and lateral borders of the expanded right gonadal vein are indicated by the short hollow arrows. (B) Axial slice of a contrast enhanced abdominal-pelvic CT scan, with an inset located in the upper right corner. The dashed white square indicates the location of the inset within the CT scan slice. Inset: The contour of the aorta (A) is indicated by the red dashed circle; the contour of the inferior vena cava (IVC) is indicated by the blue dashed oval; the contour of the expanded right gonadal vein (GV) is indicated by the white dashed ellipse and is surrounded by perivascular inflammatory stranding. (C) Duplex ultrasound (US) imaging of the right gonadal artery and vein in transverse section, with an inset located in the panel’s lower right corner. The dashed white square indicates the location of the inset within the US caption. Inset: The blue dashed oval depicts a tubular structure, containing heterogeneous echogenic material representing the enlarged thrombosed right gonadal vein; No color Doppler flow is seen within the lumen of the gonadal vein at this level. Normal color Doppler signal is seen in the adjacent right gonadal artery; the contour of the gonadal artery is indicated by the red dashed oval.

Clinical improvement was rapid over the following days and the patient was switched to an oral antibiotic regimen (amoxicillin/clavulanic acid 625 mg, tds) two days later and to oral anticoagulation (warfarin, dosed as per INR) two weeks later. Seeing that she was breastfeeding, she was not eligible for direct oral anticoagulation (DOAC). Anticoagulation was continued for a total period of three months. At six weeks follow-up, the patient’s pain had completely resolved, and at three months follow-up, a repeat transabdominal US showed complete resolution of the thrombus. The patient was assessed by a hematologist but a thrombophilia screen was not performed due to the absence of relevant thrombotic events in her personal and family histories. Of note, she had a normal BMI, was a non-smoker and was not under hormonal contraception.

Discussion

The pathophysiology of POVT can be explained by Virchow’s triad: (a) Venous stasis and (b) hypercoagulability secondary to pregnancy and the postpartum period; thought to be superimposed to these is (c) vein wall injury due to direct macroscopic trauma caused by delivery itself or indirect microscopic trauma secondary to uterine infection with subsequent spread to the adnexa and to the pelvic venous plexuses [2, 4, 5].

POVT has been found to occur more frequently on the right side [1, 2, 5, 7], possibly due to the greater length of the right ovarian vein and to the absence of competent endoluminal valves. Also, the right ovarian vein enters the inferior vena cava at an acute angle, which may make it more susceptible to compression. Finally, the dextrorotation of the enlarged uterus during pregnancy causes compression of the right ovarian vein which causes stasis of blood leading to thrombosis.

The most commonly reported symptoms of POVT are abdominal pain and fever. Its diagnosis is challenging seeing that its clinical presentation mimics other more frequent conditions such as appendicitis, acute nephrolithiasis, pyelonephritis or endometritis. Adnexal torsion, broad ligament hematoma, tubo-ovarian abscess, intussusception, and deep pelvic phlebitis constitute the broader differential [1, 2, 4, 5, 7].

Imaging therefore holds a central role in the diagnosis of POVT. The choice of radiological modality, however, is based on its availability as well as on the patient’s body habitus and past (abdominal) medical history. Pelvic magnetic resonance imaging has the highest sensitivity and specificity when compared to CT or US with Doppler, while the latter two remain more accessible and less costly [2, 8]. Repeated imaging after initiation of treatment is not routinely recommended as it comes with its own difficulties in interpretation and does not provide with further understanding regarding the type and duration of treatment [2].

There is no consensus on the best therapeutic management of POVT, and there is still debate in the literature with regard to the indication to anticoagulation. Indeed, certain authors advance that POVT is caused by puerperal pelvic infection and that treatment should be limited to antibiotics [9]. However, to date the most commonly reported medical treatment of POVT is anticoagulation, combined with broad-spectrum antibiotics when septic thrombophlebitis is suspected [8, 10]. The duration of anticoagulation depends on whether there is an underlying predisposition to thrombosis and ranges from 3 to 6 months to life-long therapy in the context of hypercoagulable disease. Heparin and oral antivitamin-K anticoagulants are most commonly used. Direct oral anticoagulants (DOAC) have the advantage of not requiring monitoring of their activity, but they are still understudied for POVT and are not compatible with breastfeeding [2, 8]. Surgical intervention including ovarian vein ligation, excision and vena cava thrombectomy is reserved for those who fail medical treatment or in whom anticoagulation is contraindicated [2].

Finally, there is also no consensus on the indication to routine thrombophilia testing after POVT. Screening of thrombophilia has revealed abnormal findings in 20% of pregnancy-related OVT, in contrast to 43% in non-pregnancy-related OVT. Basing themselves on these findings, Salomon et al. do not recommend routine screening (making an exception however for antiphospholipid antibodies) if POVT is the only manifestation of thrombosis, but rather advise an individualized approach to each case [3].

Learning points

1. POVT should be considered in all women presenting with abdominal pain and fever in the postpartum period.

2. POVT is potentially life-threatening if its diagnosis is delayed.

3. The diagnosis of POVT is clinically challenging as it mimics other more frequent conditions.

4. POVT should be looked out for on imaging studies that otherwise fail to identify a cause to the patient’s clinical presentation.