Adnexal mass — structured SAQ (15 marks)

(a) Sonographic characterisation (4 marks)

One mark for naming the system; one for the B and M features; one for the application rule; one for the validated performance. ^[1][2]

• I would characterise the mass using the International Ovarian Tumour Analysis (IOTA) Simple Rules, escalating to the ADNEX model or expert subjective assessment if the Simple Rules were inconclusive.
• Five B features (predict benign): unilocular cyst; solid components under 7 mm in largest diameter; acoustic shadows; smooth multilocular tumour under 100 mm; no detectable blood flow. Five M features (predict malignant): irregular solid tumour; ascites; at least four papillary structures; irregular multilocular solid tumour 100 mm or more; very high colour content.
• Application rule: one or more M and no B classifies malignant; the reverse classifies benign; both or neither is inconclusive, and the next step is expert subjective assessment or ADNEX (10% malignancy threshold).
• Validated performance: in the Timmerman prospective validation of 1938 masses, the Simple Rules were conclusive in 77%, with sensitivity 92% and specificity 96%; ADNEX carries a summary AUC of 0.93 for benign versus malignant across 47 external validation studies.^[1][2][3]

(b) Tumour markers in pregnancy (3 marks)

One mark for the principle; two for the physiological explanation. ^[4]

• A tumour marker panel — CA-125, AFP, hCG, inhibin, LDH — should not be sent routinely on a sonographically characterised mass in pregnancy; it is uninterpretable and will drive wrong decisions.
• CA-125 is expressed by peritoneum, decidua and amniotic fluid and rises physiologically, particularly in the first trimester and at delivery — a mid-range value tells you nothing about the mass.
• AFP, hCG and inhibin are produced by the pregnancy itself; LDH is non-specific. Interpret only extreme values or a rising trend; trust the imaging, not the panel.^[4]

(c) Most likely diagnosis and management (4 marks)

One mark for the diagnosis; two for the supporting evidence; one for the management. ^[4]

• Most likely diagnosis: a decidualised endometrioma — papillary projections with Doppler flow in a woman with known endometriosis, in pregnancy. This is the great mimic of this topic.
• Supporting evidence: in the Barcroft pregnancy-specific two-step IOTA pilot of 291 pregnant women, presumed decidualisation occurred in 31.1% of endometriomas and had resolved in 89.5% by the first postnatal scan; the ADNEX model misclassified 34% of benign masses as malignant, over half of which were decidualised endometriomas. Decidualisation is progesterone-driven stromal change producing vascular papillary projections that mimic the M features of malignancy.
• Management: resist surgery; use expert subjective assessment and serial imaging; rescan postnatally. Counsel that this is a mimic, not a cancer. If MRI is needed for problem-solving, it must be non-contrast — gadolinium is out at any gestation.^[4]

(d) Sudden pain and vomiting (4 marks)

One mark for the diagnosis; three for the management. ^[5][6]

• Diagnosis: ovarian torsion until proven otherwise. Sudden severe unilateral lower abdominal pain with vomiting in a woman with a known adnexal mass — and an IVF pregnancy, where nearly half of torsion cases cluster — is torsion; ovarian salvage is time-critical.
• Immediate actions: analgesia, intravenous access, bloods including group and save, nil by mouth, anaesthetic review, alert theatre, document the fetal heart before surgery.
• Operation: laparoscopic detorsion with ovarian conservation — a dusky torted ovary usually recovers; oophorectomy is reserved for confirmed necrosis. Technique in pregnancy: entry sited above the fundus, insufflation 12 to 15 mmHg or less, capnography, left lateral tilt, minimal uterine manipulation.
• Outcome counselling: obstetric outcomes are favourable — live birth around 92% and preterm delivery around 19% in Dvash's cohort; laparoscopy for adnexal surgery in pregnancy shows no significant increase in miscarriage or preterm delivery over laparotomy in the Cagino meta-analysis.^[5][6]