PAIN IN EARLY PREGNANCY
A 22-year-old woman attends the emergency department complaining of abdominal pain. She is 7 weeks 4 days pregnant by certain menstrual dates. She had a normal vaginal delivery at term 18 months ago. Her periods are usually regular every 27 days, with bleed- ing for 3–5 days. She has no previous gynaecological history. Her medical history involves mild asthma and two episodes of cystitis.
The pain started suddenly two nights ago and is localized to the right iliac fossa with some radiation down the right thigh. It is constant though worse on movement, so she has tended to lie still. She has not taken any analgesia as she is uncertain whether this is safe for the baby. She is always constipated and this is worse since she became pregnant. She has urinary frequency but no dysuria or haematuria. She has a slightly reduced appetite but does not feel feverish or sweaty.
Her temperature is 36.4°C, heart rate 90/min and blood pressure 96/58 mmHg. There are no signs of anaemia and she feels warm and well perfused. She is slim and the abdomen is not distended. There is focal tenderness on palpation of the right iliac fossa, with slight rebound tenderness but no guarding. Rovsing’s sign is not present. Speculum examination is unremarkable. The uterus is bulky and retroverted with no cervical excitation. The right adnexa is tender with a suggestion of ‘fullness’.
· What is the likely diagnosis and what are the differential diagnoses for the pain?
· How would you further investigate and manage this woman?
The ultrasound shows a single viable intrauterine pregnancy and haemorrhage into a corpus luteal cyst.
Urinary tract infection or calculi are excluded by the urinalysis result. Constipation is more likely to cause left-sided pain and the sudden onset of pain would perhaps be unusual. Appendicitis should be considered but the lack of systemic features, the normal tempera- ture, white count and C-reactive protein are suggestive of this not being the diagnosis.
The corpus luteum is the cystic area that develops on the ovary at the ovulation site. It may be solid, cystic or haemorrhagic and may vary in size. On colour Doppler ultrasound it has a typical ‘ring of fire’ appearance, distinguishing it from other types of ovarian cyst. In this case the ‘spider web’ or reticulated pattern of echoes within the cyst suggests that it is haemorrhagic.
Management is supportive with analgesia (paracetamol in the first instance followed by codeine derivatives if necessary) and reassurance. There is no evidence that bleeding into the corpus luteum adversely affects the pregnancy outcome. As the cyst is so large, it may be sensible to repeat an ultrasound scan in 2–4 weeks to confirm resolution.