Fluids: Their function and movement
Bernie Garrett in Fluids and Electrolytes, 2017
Follicular fluid is the fluid in a developing ovarian follicle and is rich in hyaluronic acid, one of the main components of the extracellular matrix. The granulosa cells of the developing follicles produce it. Amniotic fluid is the liquid within the uterus that bathes the developing fetus after the first few weeks of gestation. During most of the pregnancy, the fluid is produced almost entirely by fetal urination, but in the first 16 weeks of gestation, additional sources include the placenta, amniotic membranes, umbilical cord, and fetal skin. It has a number of functions that are essential for normal growth and development.22 It helps to protect the fetus from trauma to the mother's abdomen, it protects the umbilical cord from compression, it has antibacterial properties that provide some protection from infection, it acts as a reservoir of fluid and nutrients for the fetus, and it provides the necessary fluid, space, and growth factors to permit normal development of the fetal lungs.
Answers
Calver Pang, Ibraz Hussain, John Mayberry in Pre-Clinical Medicine, 2017
This question focuses on foetal physiology. The foetus makes breathing movements 1–4 hours each day. It also flushes the lungs with amniotic fluid. Amniotic fluid surrounds the foetus and acts as a mechanical protection, and provides a moist environment. There is about 10 ml produced at 8 weeks rising to one litre at 38 weeks then it falls to 300 ml at 42 weeks. During early pregnancy the fluid is formed from maternal fluids and from foetal extracellular fluid by diffusion across non-keratinised skin. Later in pregnancy the turnover of amniotic fluid is via the foetus. Amniotic fluid contains cells from both foetus and amnion, in addition to a variety of proteins, therefore it is very useful as a diagnostic tool (amniocentesis). Amniotic fluid abnormalities include polyhydramnios which is associated with oesophageal/duodenal atresia causing an inability to swallow amniotic fluid and with anencephaly. Oligohydramnios is associated with bilateral renal agenesis or posterior urethral valves (males) and resulting in an inability to excrete urine.
Amniotic Fluid Abnormalities
Tony Hollingworth in Differential Diagnosis in Obstetrics and Gynaecology: An A-Z, 2015
Despite individual variation ranging from 0.5 to 2 L, there appears to be steady regulation of this peak volume. It is fair to say that this regulation occurs with an adjustment of fetal production and removal of amniotic fluid during the pregnancy. Amniotic fluid transport to and from the amniotic cavity is controlled mainly by fetal renal excretion (production) and fetal swallowing (removal). The fetal respiratory tract, fetal membranes, and placenta play a small part in the transport of amniotic fluid. Fetal urine production appears to begin at approximately 9 weeks’ gestation, but it is not the primary source of amniotic fluid until between 14 and 18 weeks’ gestation. The latter finding is important in understanding abnormalities of AFV in the early and mid second trimester. Amniotic fluid fulfils many roles in the development of the fetus, including protection from trauma, cord compression, and infection (bacteriostatic properties), as well as facilitating fetal lung, musculoskeletal, and gastrointestinal development.
Prenatal exposure to isolated amniotic fluid disorders and the risk for long-term cardiovascular morbidity in the offspring
Published in Gynecological Endocrinology, 2020
Ortal Hadar, Tamar Wainstock, Eyal Sheiner, Gali Pariente
Amniotic fluid (AF) is essential for normal growth and development of the fetus. It protects the fetus from trauma and infection through its antibacterial properties and provides fluids and growth factors, generates space which prevents compression of the umbilical cord and placenta [1]. Therefore, AF volume (AFV) measurement is an important parameter in the assessment of fetal well-being. AF surrounds the fetus in the amniotic sac and is generated from maternal plasma in the first weeks of pregnancy [1]. When fetal kidneys mature in the 16th week of pregnancy, fetal urine becomes the major contributor of the AFV [2]. The semi-quantitative estimates of AFV include the amniotic fluid index (AFI) which is the sum of the maximal vertical AF pocket diameter in each quadrant of the uterus and the single deepest vertical pocket (DVP). Normal ranges of AFV include a DVP depth at or above 2 cm and below 8 cm or an AFI between 5 and 24 cm [2,3].
Predicting previable preterm premature rupture of membranes (pPPROM) before 24 weeks: maternal and fetal/neonatal risk factors for survival
Published in Journal of Obstetrics and Gynaecology, 2022
Aylin Günes, Hüseyin Kiyak, Semra Yüksel, Gökhan Bolluk, Rabia Merve Erbiyik, Ali Gedikbasi
The amniotic fluid volume had a significant influence on pregnancy outcomes and neonatal complications. Although spontaneous healing of foetal membranes occurs in 1–2% of gestations after amniocentesis and 5–30% of gestations after fetoscopy, spontaneous resealing is infrequent after spontaneous rupture of membranes (Devlieger et al. 2006; Jain and Sciscione 2011). We demonstrated a statistically significant relationship between neonatal survival and the presence of oligo- or an-hydramnios (p = .001 and p = .013, respectively). There was a strong relationship between oligohydramnios or anhydramnios and poor neonatal survival (Shenker et al. 1991; Kilbride and Thibeault 2001; Spong 2001; Muris et al. 2007; Waters and Mercer 2009; Williams et al. 2009; van Teeffelen et al. 2010; Williams et al. 2012). Specifically, we found an anhydramnios rate of 6.73% in surviving infants and 28.3% in non-surviving infants. In a study that included 71 pregnancies with severe persistent oligohydramnios and PPROM prior to 25 weeks’ gestation, 51 infants survived, 11 had pulmonary hypoplasia, and 15 had joint contractures or positional limb deformities. The short-term outcomes of the surviving infants were good (Dinsmoor et al. 2004); however, all deaths in another study occurred in pregnancies in which the largest pocket was <2 cm (Williams et al. 2009). Other studies with PPROM greater than 26 gestational weeks showed similar unfavourable outcome for neonatal morbidity and mortality for amniotic fluid index less than 5 cm (Mousavi et al. 2018).
Physiology of intra‐abdominal volume during pregnancy
Published in Journal of Obstetrics and Gynaecology, 2021
Aleksei Petrovich Petrenko, Camil Castelo-Branco, Dimitry Vasilevich Marshalov, Alexander Valerievich Kuligin, Yuliya Sergeevna Mysovskaya, Efim Munevich Shifman, Adam Muhamed Rasulovich Abdulaev
In our study, the uterus represented 0.65% of the IAV at the beginning of pregnancy, similar to the results of Sheth et al. (2017). However, with an increase of 143.5-fold at full-term, the uterus represents 55.97% of the IAV. This gain may be explained by changes observed in placenta, amniotic fluid and the foetus along pregnancy. Placental growth occurs in three phases: a linear increase up to week 24 (∼150 g), followed by a steeper, linear increase during the third trimester and reaching a plateau at term (∼600–700 g, range 500–1000 g; Almog et al. 2011). Amniotic fluid also accumulates to up to 3 L until the end of a healthy pregnancy (Wallace et al. 2013). Finally, the foetus grows at a relatively consistent speed of ∼1 kg by the 28th week of gestation, and thereafter, over the next 12 weeks, the foetus gains more than two-thirds of its final weight (∼2.5 kg; Institute of Medicine and National Research Council 2009; Most et al. 2018).
Related Knowledge Centers
- Amniotic Sac
- Fetus
- Gestational Sac
- Keratin
- Protein
- Lipid
- Carbohydrate
- Blood Plasma
- Gravidity & Parity
- Electrolyte