The intra-amniotic pressure

Coren, R. L.; Csapo, A.I.

doi:10.1016/s0002-9378(16)35490-4

Cited by 37 publications

(12 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In contrast, we measured AP before other procedures to avoid stimulating contractions, and used a fixed reference point comparable between subjects. There are two components to AP: firstly that due to uterine tension, which according to Pascal's law is equal and uniform within the uterus (Coren & Csapo 1963), and secondly a gravitational componenf that varies vertically. AP referenced to a variable point will thus vary with the position of that point within the cavity (Fisk et al .…”

Section: Discussionmentioning

confidence: 99%

“…Our results demonstrate that AP rises in late pregnancy, whereas it had previously been assumed to fall, due to a stable uterine radius and thus volume (Reynolds 1965). Although numerous geometrical shapes have been used to describe the uterine cavity, it may be considered in terms of Laplace's law as a sphere, a mathematical simplification with no significant consequence on results (Coren & Csapo 1963). Thus pressure within the sphere is a function of T/r, where T is the wall tension and r the radius.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Normal amniotic pressure throughout gestation

Fisk

Ronderos-Dumit

Tannirandorn

et al. 1992

BJOG

View full text Add to dashboard Cite

Objective To characterize amniotic pressure (AP) in pregnancies with normal amniotic fluid volume. Design Observational study, mainly cross‐sectional. Setting Fetal medicine unit within a tertiary referral hospital. Subjects Patients undergoing transamniotic invasive procedures in whom amniotic fluid volume was subjectively assessed as normal on ultrasound. Those beyond 16 weeks with a deepest vertical pool on ultrasound <3.0 or >8.0 cm were excluded. Overall 194 pregnancies were studied on 232 occasions between 7 and 38 weeks gestation. Interventions Manometry readings referenced to the top of the maternal abdomen were obtained via a fluid‐filled line from the needle hub and either connected to a pressure transducer (n= 190) or held vertically against a ruler (n−42). Main outcome measures AP in mm Hg, AP corrected for gestational age (z scores), semi‐quantitative ultrasonic indices of amniotic fluid volume, clinical variables. Results AP in singleton pregnancies increased with advancing gestation (P<0.001), and the sigmoid‐shaped regression curve plateaued in the mid‐trimester. AP z scores were not influenced by volume‐related phenomena such as twin gestation, the deepest vertical pool, or amniotic fluid index, nor by maternal age, parity, gravidity, fetal sex, or subsequent spontaneous preterm delivery. Conclusions These findings suggest that AP is not principally determined by intrauterine volume. We speculate that AP, which reflects change in uterine tension as a function of radius, may instead be determined by gestation‐specific anatomical and hormonal influences on gravid uterine musculature. A reference range for AP has been constructed for use in amnioinfusion and amnioreduction procedures.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Normal amniotic pressure throughout gestation

Fisk

Ronderos-Dumit

Tannirandorn

et al. 1992

BJOG

View full text Add to dashboard Cite

show abstract

“…The finding that the rate of rise of intrauterine pressure was significantly elevated after treatment suggests that relaxin improves myometrial co-ordination. This conclusion is based on theoretical (Coren & Csapo, 1963) and experimental (Csapo & Takeda, 1965) evidence that the rate of development of pressure within a uterus is determined by the degree of electrical synchronization within the myometrium. The finding that rat relaxin has this property is consistent with similar findings reported for porcine relaxin (Downing, Bradshaw & Porter, 1980), and lends additional support to the contention that relaxin may mediate some of the actions of oestrogens on the uterus (Steinetz, Beach, Blye & Kroc, 1957) because oestradiol is also known to enhance the rate of rise of intrauterine pressure (Downing, Lye, Bradshaw & Porter, 1978), amongst other actions resembling those of relaxin (Steinetz et ai, 1957).…”

Section: Discussionmentioning

confidence: 99%

Demonstration of some of the physiological properties of rat relaxin

Bradshaw¹,

Downing²,

Moffatt³

et al. 1981

Reproduction

View full text Add to dashboard Cite

Summary. Relaxin was extracted from the ovaries of pregnant rats. Material possessing uterine relaxing activity in vitro was eluted in three peaks from Sephadex G.50 columns. The 'G3 peak' material eluting in a position comparable to that of porcine relaxin inhibited myometrial activity of rats in vivo, improved the rate of rise of pressure of intrauterine pressure cycles in vivo, and, when administered to rats following progesterone and oestrogen priming, increased the distensibility of the cervix in vitro. This material also stimulated inter-pubic ligament formation in the mouse. This rat relaxin material therefore exhibits biological actions in the rat similar to those previously assigned to porcine relaxin.

show abstract

“…However, by making this conclusion it should be remembered, that the contraction complexes developed by the uterus in midpregnancy indicated uterine incoordination in many instances. This means, that probably only a segment of the uterine wall was active, whereas the surrounding segments might have been stretched which invalidates the effectiveness of the contractions (21). The patients at term included in the present study were selected from a larger induction series, where rupture of the membranes and cervical dilatation in some cases occurred during the course of the 6 hour stimulation period.…”

Section: Discussionmentioning

confidence: 99%

Response of the Pregnant Human Uterus to Low and High Doses of Prostaglandin E₁ and E₂

Roth-Brandel

1971

Acta Obstet Gynecol Scand

View full text Add to dashboard Cite

Uterine sensitivity to low doses of prostaglandin E, was compared at midpregnancy and at term. An analysis of the amniotic pressure recordings revealed that the uterus in midpregnancy responded by increased contractility to an infusion rate of the same order as that, commonly used for induction of labour at term. However, the absolute intensity of the contractions was significantly higher at term than at midpregnancy. Intravenous infusion of high doses of prostaglandin E, (maximum dose without consistent subjective side effects) at midpregnancy stimulated the uterus to frequent contractions (6-8 contractions per 10 min) of gradually increasing intensity, which reached an average value of 35 mmHg following 6 hours of infusion. T h e individual uterine response to prostaglandin varied considerably from one case to another. The "maximum tolerable infusion rate" which could be administered without major subjective side effects also varied within a wide range.

show abstract

The intra-amniotic pressure

Cited by 37 publications

References 3 publications

Normal amniotic pressure throughout gestation

Normal amniotic pressure throughout gestation

Demonstration of some of the physiological properties of rat relaxin

Response of the Pregnant Human Uterus to Low and High Doses of Prostaglandin E₁ and E₂

Contact Info

Product

Resources

About

The intra-amniotic pressure

Cited by 37 publications

References 3 publications

Normal amniotic pressure throughout gestation

Normal amniotic pressure throughout gestation

Demonstration of some of the physiological properties of rat relaxin

Response of the Pregnant Human Uterus to Low and High Doses of Prostaglandin E1 and E2

Contact Info

Product

Resources

About

Response of the Pregnant Human Uterus to Low and High Doses of Prostaglandin E₁ and E₂