i 5 88 



HANDBOOK OF PHYSIOLOGY 



CIRCULATION II 



fig. 3. Arterial pattern of uterus. Cleared preparation. One 

 small myoma on right side. [From Faulkner (77).] 



by Davidsohn (64) many years ago. Further assurance 

 of venous return exists by way of multiple venous 

 connections to the vertebral vein system, as Batson 

 (27, 28) has emphasized (see also Jeffcoate (117). 

 The ovarian "vein" in part is in reality the tubo- 

 ovarian pampiniform plexus which pours blood into 

 the inferior vena cava from the right side, or the 

 renal vein on the left. Other interconnections exist, 

 also. However, sudden occlusion of the inferior vena 

 cava can cause separation of the placenta [Mengert 

 et al. (150)]. Donnelly (66) relates noninduced pla- 

 cental separation to gross abnormalities of the 

 placenta. 



All in all, within the uterus itself and in the venous 

 systems of the abdominal cavity and body wall, there 

 are abundant intercommunications, so that oppor- 

 tunity for obstruction to the venous drainage of uterine 

 blood is minimized. Barcroft & Rothschild (21) 

 emphasized this with regard to the rabbit; Bieniarz 

 (31) has stressed it in relation to the human. Oughtred 

 & Reynolds (165) demonstrated the operation of the 



collateral abdominal and somatic venous systems in 

 the dog when the inferior and superior vena cava 

 were blocked at various levels. 



FUNCTIONAL IMPLICATIONS OF VENOUS DRAINAGE 



Problems that arise from malfunctioning of the 

 venous system are recognized. In general, they are 

 twofold. In animals having an erect posture, at least 

 in the human, pelvic congestion which is correctable 

 by operative procedures is known [Taylor (230), 

 Curtis et al. (58)]. These contribute to endocrine 

 disorders and a variety of clinical entities. The second 

 group of functional disorders is related to distribution 

 of the vascular loads upon the circulatory system in 

 late pregnancy [Bieniarz (30)]. When the placenta in 

 the human is implanted high in the uterus, drainage 

 by way of the ovarian pathways predominates. When 

 this happens, albuminuria, hypertension, and even 

 toxemia frequently occur. A continuous discharge of 

 several hundred milliliters of blood per minute into 

 the vena cava or renal vein may complicate renal and 

 adrenal blood flow, Bieniarz (31) postulates. Ligation 

 of the vena cava above the renal veins affects renal 

 function and possibly adrenal gland activities as well 

 [Karaev (126)]. When, on the other hand, the pla- 

 centa is implanted low in the uterus simplex, placenta 

 praevia and hemorrhage more commonly occur 

 [Bieniarz (30)]. The former condition is more frequent 

 in primigravidas, the latter, in multiparas. 



Although ovarian vein physiology has been im- 

 plicated by deduction in the incidence of toxemia 

 [Bieniarz (30)], other mechanisms are suspect, also. 

 Placental ischemia as a factor is considered by Page 

 (168). Saito (214) produced toxemic signs in animals 

 with human placental extracts and this is said to be 

 an allergic reaction by Lin ( 136) who sensitized rats to 

 placental tissue by injection of placental tissue 5 

 months before. However, killing of the fetuses in 

 hypertensive rats leads to lowering of blood pressure 

 [Page (166)]. Examining the problem experimentally, 

 Ogden et al. (162) placed Goldblatt clamps on uterine 

 arteries in pregnant rabbits and observed that pro- 

 gressive hypertension developed promptly. This was 

 relieved by removal of the clamps. Grollman (87) 

 observed that induced hypertension in rats is reduced 

 by normal pregnancy, but not by pseudopregnancy. 

 (See below discussion of the placenta as an A-V 



fig. 4 (facing page). The uterine drainage system during pregnancy (sagittal view). Different 

 visceral and parietal venous drainage routes are shown in different colors. [Reprinted by permission 

 from Bieniarz (31).] 



