Male pelvic organs

Bony framework and features of the male pelvis

The pelvic bones together with the sacrum form a closed ring. It is divided into the greater pelvis (serves as support for abdominal organs) and the lesser pelvis — a tapering bony canal. The walls of the lesser pelvis are formed by the sacrum, coccyx, ischium, and pubis, as well as the ligamentous apparatus and obturator membranes.

Unlike the female pelvis, the male pelvis is narrower and longer. The angle formed by the inferior rami of the pubic bones is called the subpubic angle and in men measures 70–75° (in women, it is the pubic arch with an angle greater than 90°).

Peritoneal pouches in men

The parietal peritoneum, as it passes from the pelvic walls onto the organs, forms recesses. In men, there is only one such recess in the lesser pelvis — the rectovesical pouch (excavatio rectovesicalis).

• Topography: The peritoneum descends along the posterior wall of the urinary bladder, covers the internal borders of the ampullae of the ductus deferentes (ampullae ductus deferentis) and the apices of the seminal vesicles (vesiculae seminales). It does not reach the base of the prostate gland by approximately 1.0–1.5 cm.
• Boundaries: Laterally, the pouch is bounded by the rectovesical folds (plicae rectovesicales), and its fundus is firmly fixed to the rectoprostatic fascia of Denonvilliers.
• Clinical significance: This is the lowest point of the pelvic part of the peritoneal cavity in men. In acute surgical pathologies (appendicitis, parenchymal organ trauma, perforated ulcers), blood, pus, or inflammatory exudate accumulates here.

Testicular developmental anomalies

To assess gonadal function in boys, testicular ultrasound and laboratory blood tests for sex hormones and gonadotrophins are used. Among anatomical developmental defects, the most common are:

1. Monorchism — congenital absence of one testis.
2. Cryptorchidism — delayed descent of one or both testes into the scrotum. The testis may stop in the abdominal cavity or inguinal canal. Due to improper temperature conditions, the germinal epithelium degenerates, and the number of spermatogonia decreases. Bilateral involvement inevitably leads to impaired spermatogenesis and infertility.

Genetic disorders and hermaphroditism

Sex chromosome abnormalities in men often manifest as delayed puberty, infertility, and altered gonad size.

• Klinefelter syndrome (47,XXY karyotype): tall stature, eunuchoid habitus, hypoplasia (small size) of the testes.
• Fragile X syndrome: intellectual disability combined with macrorchism (enlargement of the testes).
• 47,XYY karyotype: tall stature, aggressiveness, delayed speech development.

When sexual differentiation is impaired, external genitalia have an intermediate structure. This can be true hermaphroditism (presence of ovotestis — combined ovarian and testicular tissue) or male pseudohermaphroditism (incomplete masculinization with a male karyotype due to testicular dysgenesis or impaired androgen synthesis).

Pelvic renal dystopia

Sometimes during embryogenesis, the kidney fails to ascend into the lumbar region and remains in the lesser pelvis. Pelvic kidneys are at high risk of trauma, urolithiasis, and pelviureteric junction obstruction.

• Fusion of two pelvic kidneys forms a pancake kidney (pancake kidney).
• Crossed fused ectopia (crossed fused renal ectopia) occurs more often in men than in women, when one kidney crosses the midline and fuses with the other. In this case, the ureters open into the bladder orthotopically (in the typical location).

Class and exam questions

What else to study on this topic

• Horseshoe kidney and its topography relative to major vessels
• Renal vessel anomalies in renal ectopia
• Female pelvis: dimensions, conjugate diameters, and the pouch of Douglas
• Technique for performing culdocentesis
• Female pseudohermaphroditism and congenital adrenal hyperplasia

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.