Urinary And Genital System

KIDNEYS AND URETERS Renal vessels usually are opened lengthwise from the aorta or inferior vena cava to the hilus. We routinely incise the kidneys in situ. The fibrous and adipose capsule is tripped, using the unsevered renal vessels as anchor. This prevents the organs from slipping out of one's hand after they have been removed from the retroperitoneal fat tissue. The kidneys are then excised from their convexity toward the hilus, exposing the renal pelvis. During this procedure the organ can be held in a firm grip by applying some tension to the renal vessels.

The ureters are opened lengthwise, starting from the renal pelvis and, if necessary, cutting through some undissected parenchyma at the lower pole of the kidneys. The renal vessels and ureters can now be severed, or the kidneys can be removed together with the aorta, inferior vena cava, and pelvic organs. Blocks for histologic examination should include renal cortex, medulla with a papilla, and a portion of the renal pelvis.

If retroperitoneal disease processes involve more than one organ, for example, after rupture of abdominal aortic aneuryms or after renal cell carcinomas have spread into veins (Fig. 5-8) it may be necessary to remove an organ block for proper dissection.

Perfusion Fixation A cannula is tied into the renal artery and the kidneys are perfused with 10% formalin solution. Because the renal veins often contain blood clots, perfusion with 0.9% saline, followed after 20 min by perfusion with 7% formalinsaline has been recommended (14).

Renal Arteriography Arteriograms can be prepared in situ (Fig. 5-9), after en block removal of the abdominal aorta and kidneys, or on isolated organs. Clinical contrast media or barium sulfate-gelatin mixtures give excellent results. A catheter is tied into the celiac artery in situ or after removal of the organ block and all nonrenal arteries are tied and both ends of the aorta are clamped.

Renal Venography The techniques are essentially similar to the ones used for arteriography. We have prepared in situ venograms by injection of contrast medium into a segment of the inferior vena cava that was sealed off by inflatable cuffs (Fig. 5-10). The tube with the cuffs can be introduced from the iliac or femoral veins without handling of the inferior vena cava system. By moving the cuffs higher, excellent hepatic veno-grams can be prepared.

Urography Retrograde urograms are easy to prepare with any of the conventional contrast media. The ureter is cannu-lated either from the urinary bladder or through the wall of the distal ureter. This can be particularly helpful for the detection of congenital urethral valves (Figs. 5-11 and 5-12).

Preparation of Plastic Casts Plastic casts can be used for the demonstration of the renal vasculature, the pelvic system, and cysts or other abnormal cavities. The methods are similar to those described for other organs. Again, the instructions supplied by the manufacturer should be followed carefully.

PELVIC ORGANS Intravascular formalin injection or freezing methods have been used to harden pelvic organs in their natural position (16). The vascular system of the pelvic can be injected from the internal iliac artery. Corrosion specimens are prepared by the usual techniques.

Urinary Bladder Fixation in the distended position is achieved by injecting formalin solution through a catheter. Urine in the bladder must be removed first. The urinary bladder is left intact until fixation is completed. The upper half of the bladder is then removed and the base of the bladder is exposed. This technique is particularly recommended in cases of benign pro-static hyperplasia with urethral obstruction or urinary bladder tumors in the area of the trigone. Some tumors or abscesses are better exposed by frontal sections through the base of the urinary bladder and prostate.

Fig. 5-8. Anterior view of kidneys, inferior vena cava, and abdominal aorta. Note renal cell carcinoma in upper pole of right kidney and large tumor nodule in the lumen of the inferior vena cava, just below the entrance of the left renal vein.

Penis and Male Urethra Most pathologists do not routinely dissect these organs. Congenital urethral valves (Figs. 5-11 and 5-12), strictures, and tumors are the main indications for study. The penis, usually without surrounding skin, should be left attached to the urinary bladder. This can be achieved by either sawing out a portion of the pubic bone or by pulling the penis through the pubic arch. These maneuvers require preparatory dissection of soft tissue and appropriate incisions of the skin of the penis. The urethra should be opened lengthwise in the anterior midline. Histologic sections through urethra and corpora cavernosa are usually taken in a frontal plane, that is, perpendicular to the axis of the urethra.

Urethra valves can best be located by injecting radiopaque material into the urinary bladder (Fig. 5-11). The urethra should then be opened along the anterior midline against the direction of the flow of urine (Fig. 5-12). This will help prevent laceration of the delicate valves.

Fixation of the corpora cavernosa can be achieved by injecting formalin solution or gelatin-formalin through the vena dor-salis penis.

Uterus The pregnant uterus can be fixed by first puncturing the uterus through the anterior abdominal wall and replacing the amniotic fluid with formalin solution. After the prefixed uterus has been opened, the fetus is perfused with formalin solution through the umbilical cord. If one intends to preserve uterus and fetus as one specimen, a formalin-gelatin mixture is injected into the cavity of the uterus.

Placenta In some institutions the placenta is routinely discarded. Autopsy pathologists should discourage such practices, especially with autopsies on stillbirths (see Part II, "Stillbirth") and neonates. In these cases, pathologists always need to study the placenta also. The following procedures for gross examination are suggested (17,18).

First, the placenta should be weighed because both low placental weight and overweight placentas generally are associated with other fetal or neonatal abnormalities (19). For expected placental weights, see Part III, Appendix (page 556). If the placenta cannot be studied further after delivery, it should be stored in a closed container in the refrigerator. If one wants to ascertain the original position of the placenta by demonstrating the site of the uterine cornua and the point of rupture of the membranes, one can begin the examination with the reconstruction, in a tank of saline, of the fetal membranous bag. The narrowest width of membranes is measured. If there are no velamentous vessels, the bag is trimmed from the placenta. A sausage-shaped roll of membrane is fixed for histologic study, with the site of the rupture innermost. The cord is then measured and its surface and cross-sections inspected; the vessels are counted on cross-sections. A segment of the umbilical cord is fixed for histologic study. After the cord is cut near its insertion and the

Fig. 5-9. In situ renal arteriograms. (A) Polyethylene catheter in superior mesenteric artery. Main renal arteries had minimal histologic evidence of atherosclerosis (arrows). Cross-clamping of aorta is evident at base of film (arrow). (B) Evidence of narrowing in both renal arteries but more pronounced in right renal artery (arrow). Histologically, stenosis was graded as severe. Adapted with permission from ref. (15).

Fig. 5-9. In situ renal arteriograms. (A) Polyethylene catheter in superior mesenteric artery. Main renal arteries had minimal histologic evidence of atherosclerosis (arrows). Cross-clamping of aorta is evident at base of film (arrow). (B) Evidence of narrowing in both renal arteries but more pronounced in right renal artery (arrow). Histologically, stenosis was graded as severe. Adapted with permission from ref. (15).

membranes removed, the placenta is weighed and measured. The placenta should be kept moist. The fetal and maternal surfaces are inspected. The yolk sac is searched for. If cotyledons are missing, milk injection (see below) or other injection procedures help to distinguish true tissue defects from artifacts of handling. The placenta is then cut into thin slices with a long-bladed knife. Blood is wiped off and the cut surfaces are inspected. Grossly abnormal areas are placed in Bouin's solution for histologic study; after a few hours, the tissue is trimmed and refixed. Routinely, three section are taken from central areas of the placenta where chorionic vessels can be included.

The examination ofplacentas in multiple pregnancies requires special precautions. A longitudinal strip is cut from the portion of fusion or approximation of the membranous sacs, leaving the placenta intact, and a roll is prepared for histologic study. (One also can prepare a "T-section"—that is, an area of fused twinpla-centa with dividing membranes extending above that may show two amnions or two amnions and two chorions. Unfortunately,

T-sections interfere with subsequent vascular injection.) The dividing membranes are then peeled apart with the aid of forceps. If two chorions are present, separation attempts will disrupt villous placental tissue. The placenta is now weighed and measured.

Vascular injection is necessary to separate the vascular beds of the fused dichorionic placenta. Injections also are used to decide whether vascular communications exist and to determine their nature and number. Because of artifactual villous disruptions, usually only selected areas can be injected, using milk or other injection media. Shunts are absent in all dichorial twins but will be seen in almost all monochorial twin placentas. The "vascular equator" can be identified after the amniotic membranes have been stripped. At various sites in this area, milk is injected into arteries near presumed common vascular channels. About SOSO mL of milk usually is necessary at each site to determine whether fluid returns to the same infant or its partner through anastomoses. During the injection, blood must be allowed to escape from where the umbilical cords have been cut near their insertions.

Fig. 5-10. Normal renal venogram. Rubber tube with two inflatable cuffs was introduced to seal off inferior vena cava above and below renal veins. Barium sulfate-gelatin mixture was injected through midportion of tube. There is also filling of lumbar, prevertebral, adrenal, and left testicular veins.

Fig. 5-10. Normal renal venogram. Rubber tube with two inflatable cuffs was introduced to seal off inferior vena cava above and below renal veins. Barium sulfate-gelatin mixture was injected through midportion of tube. There is also filling of lumbar, prevertebral, adrenal, and left testicular veins.

Fig. 5-11. Urogram in patient with congenital urethral valves. Some radiopaque material was injected into the urinary bladder and attempts were made to squeeze it onto the urethra. The radiograph shows that this was not possible.

Fig. 5-12. Urethra with congenital valves. The penis and urinary bladder have been removed in continuity as described in the text, and opened in the anterior midline. The arrow shows the delicate urethral valves.
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