Reproductive tract disorders

Uterus in pregnancy and after delivery

• Pregnancy enlarges the uterus mainly by hypertrophy of smooth muscle cells (oestrogen driven), with some hyperplasia. By about 4 months the decidua capsularis fuses with the decidua parietalis, obliterating the uterine cavity. After delivery the uterus shrinks by atrophy (autophagy).
• Cervical ectropion in pregnancy, the pill and adolescence: oestrogen everts the columnar endocervical epithelium onto the ectocervix.
• Primary postpartum haemorrhage: commonest cause uterine atony (tone), then trauma, tissue (retained products) and thrombin (coagulopathy); bleeding from the placental bed is normally stopped by myometrial contraction (living ligatures).
• Progestogens (or pregnancy) decidualise the endometrium: abundant plump stroma with few, inactive glands.

Uterine lesions

• Fibroids (leiomyomas): monoclonal smooth muscle tumours (MED12), oestrogen-dependent. Submucous ones bleed most. Degenerations: hyaline (commonest), red in pregnancy, cystic, calcific.
• Lipoleiomyoma: a fat-density mass (about −90 HU) arising within the myometrium; always find the organ of origin of a fatty pelvic mass (ovarian dermoid is the commoner fatty mass).
• Adenomyosis: junctional zone over 12 mm on MRI; boggy tender uterus.
• Endometrial hyperplasia: unopposed oestrogen (anovulation, PCOS, obesity, tamoxifen, granulosa cell tumour) causes heavy irregular bleeding.

• Endometrial cancer spreads mainly by direct myometrial invasion and lymphatics; blood spread is late and least likely. A young woman with endometrial cancer, a mother with the same and a brother with colon cancer has Lynch syndrome (mismatch repair genes, e.g. MLH1, MSH2).
• Asherman syndrome: curettage destroys the stratum basalis.
• Uterine arteriovenous malformation: after curettage or miscarriage; hCG negative, empty cavity, tubular anechoic spaces in the myometrium with turbulent, high-velocity, low-resistance flow. Retained products instead show a vascular echogenic mass in the cavity with positive hCG.
• IUCD perforation: threads missing, pregnancy test negative, empty cavity on ultrasound but the device seen on an abdominal radiograph; copper devices are removed laparoscopically because they cause adhesions.

Cervix

• HPV 16 and 18: E6 degrades p53, E7 inactivates Rb; koilocytes. Cancer begins in the transformation zone.
• Diagnosis: screening cytology or HPV test; abnormal smear (dyskaryosis) is followed by colposcopy with biopsy, and CIN 2–3 is treated by large loop excision of the transformation zone (LLETZ). Invasive cancer is diagnosed by biopsy (histology).
• Carcinoma in situ on cytology: high nuclear to cytoplasmic ratio, hyperchromatic irregular nuclei throughout the epithelium.
• Spread: parametrium (ureteric obstruction), pelvic then para-aortic nodes.

Pelvic infection and vaginitis

• Tubo-ovarian abscess: fever, pain and cervical motion tenderness with a thick-walled multilocular adnexal mass; infection ascends from the cervix through the uterus and tube (gonococcus, chlamydia, anaerobes). It can mimic an ovarian tumour.
• Trichomonas vaginalis: frothy yellow-green discharge, strawberry cervix, motile flagellates on wet mount; no cyst stage, spread sexually; treat both partners with metronidazole.

Early pregnancy on ultrasound

Ovary and adnexa

• Functional cysts: follicular, corpus luteum (ring of fire).
• Paraovarian cyst: thin-walled cyst in the broad ligament (mesonephric remnant) with a normal ovary seen separately that moves away from it under probe pressure; does not change with the cycle.
• Fetal ovarian cyst: in a female fetus in the third trimester, maternal and placental hormones (hCG, oestrogen) stimulate follicles; most regress after birth; a complex cyst with a fluid level may have torted.

• Ovarian fibroma (and Brenner tumour, uterine fibroids) is very dark on T2, like muscle, because of dense collagen with little free water; enhances slowly.
• OHSS: hCG-driven VEGF capillary leak.

Prostate

• A normal adult prostate weighs about 20 g (about 20 mL).
• MRI: the normal peripheral zone is bright on T2 because its glands are full of fluid; cancer is dark because packed tumour cells replace the fluid-filled glands, and it restricts diffusion. Prostatitis and post-biopsy blood can mimic it.
• Finasteride (5α-reductase inhibitor) roughly halves PSA after 6–12 months, so double the measured value; a rising PSA on it is suspicious.
• Castration-resistant cancer: the tumour makes its own androgens. Abiraterone inhibits CYP17 (17α-hydroxylase/17,20-lyase), blocking androgen synthesis in adrenals and tumour; it is given with prednisolone because blocked cortisol synthesis raises ACTH and mineralocorticoids (hypokalaemia, hypertension).
• Chronic bacterial prostatitis: recurrent E. coli UTIs and perineal pain; drugs must be lipid soluble (fluoroquinolones, trimethoprim) to cross the prostatic epithelium into acidic prostatic fluid. Calcifications harbour bacteria.
• Spread to the spine via the vertebral venous plexus; sclerotic metastases.

Testis and scrotum

• Gynaecomastia with a testicular tumour: very high hCG acts on LH receptors and stimulates Leydig cells to make oestradiol (aromatase); it can also cause hyperthyroidism.
• Burned-out tumour: retroperitoneal nodes and raised hCG with only a small scar and coarse calcification in the testis.
• Testis lymph drains to para-aortic nodes; scrotal skin (chimney sweep's soot carcinoma) drains to superficial inguinal nodes on the same side.
• Torsion: high transverse testis, absent cremasteric reflex, absent Doppler flow, twisted cord; salvage depends mainly on time since the onset of pain (best within 6 hours). Never let imaging delay exploration.
• Undescended testis: most often in the inguinal canal; retractile testes can be brought down. Seminoma risk persists after orchidopexy.
• Encysted hydrocele of the cord: a transilluminating cyst above the testis that moves with traction on it: the middle segment of the processus vaginalis stays patent while both ends close (canal of Nuck cyst in girls).
• Low-flow priapism in sickle cell disease: sickled cells block venous outflow from the corpora; dark, hypoxic, acidotic blood and no arterial flow; urgent aspiration.
• Breaching the blood–testis barrier (vasectomy) causes antisperm antibodies.

Remember Peripheral zone for prostate cancer, transition zone for hyperplasia; collagen makes pelvic masses dark on T2.

Exam trap A pseudosac in the uterus with an adnexal mass is an ectopic pregnancy, not an early intrauterine one.

Exam trap Never biopsy a testicular mass through the scrotum; it opens a new lymphatic route.

How FCPS asks about this

• Commonest cause of primary PPH: uterine atony.
• Endometrial hyperplasia cause: unopposed oestrogen; endometrial cancer with family colon cancer: Lynch syndrome.
• Abiraterone mechanism: CYP17 inhibition of androgen synthesis.
• PSA on finasteride: double the value.
• Stains supporting seminoma: OCT3/4 and PLAP.
• Scrotal skin cancer in a chimney sweep: superficial inguinal nodes.
• Factor predicting testicular salvage in torsion: time since onset of pain.