pelvimetry

骨盤計測法 　

WordNet

1. measurement of the dimensions of the bony birth canal (to determine whether vaginal birth is possible)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/05 17:10:47」(JST)

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Pelvimeter

Pelvimetry is the assessment of the female pelvis in relation to the birth of a baby. Traditional obstetrical services relied heavily on pelvimetry in the conduct of delivery in order to decide if natural or operative vaginal delivery was possible or if and when to use a cesarean section.

Use

Pelvimetry used to be performed routinely to discern if spontaneous labour was medically advisable. Women whose pelvises were deemed too small received caesarean sections instead of birthing naturally. Research indicates that pelvimetry is not a useful diagnostic tool for CPD (see below) and that in all cases spontaneous labour and birthing should be facilitated.

A woman's pelvis loosens up before birth (with the help of hormones), and an upright and/or squatting woman can birth a considerably larger baby. A woman in the lithotomy (lying on her back, legs elevated) is more than likely not going to push a larger than average baby out, due to the size of outlet that this position creates.

Cephalo-pelvic disproportion: CPD

Main article: Cephalopelvic disproportion

Cephalo-pelvic disproportion exists when the capacity of the pelvis is inadequate to allow the fetus to negotiate the birth canal.

Terminology

The terms used in pelvimetry are commonly used in obstetrics. Clinical pelvimetry attempts to assess the pelvis by clinical examination. Pelvimetry can also be done by radiography and MRI.

Pelvic planes

Diameters of inferior aperture of lesser pelvis (female).

• Pelvic inlet: The line between the narrowest bony points formed by the sacral promontory and the inner pubic arch is termed obstetrical conjugate: It should be 11.5 cm or more. This anteroposterior line at the inlet is 2 cm less than the diagonal conjugate (distance from undersurface of pubic arch to sacral promontory). The transverse diameter of the pelvic inlet measures 13.5 cm.
• Midpelvis: The line between the narrowest bone points connects the ischial spines; it typically exceeds 12 cm.
• Pelvic outlet: The distance between the ischial tuberosities (normally > 10 cm), and the angulation of the pubic arch.

Pelvic types

Traditional obstetrics characterizes four types of pelvises:

• Gynecoid: Ideal shape, with round to slightly oval (obstetrical inlet slightly less transverse) inlet: best chances for normal vaginal delivery.
• Android: triangular inlet, and prominent ischial spines, more angulated pubic arch.
• Anthropoid: the widest transverse diameter is less than the anteroposterior (obstetrical) diameter.
• Platypelloid: Flat inlet with shortened obstetrical diameter.

Fetal relationship

• Engagement: The fetus is engaged if the widest leading part (typically the widest circumference of the head) is negotiating the inlet.
• Station: Relationship of the bony presenting part of the fetus to the maternal ischial spines. If at the level of the spines it is at “0 (zero)” station, if it passed it by 2cm it is at “+2” station.
• Attitude: Relationship of fetal head to spine: flexed, neutral (“military”), or extended attitudes are possible.
• Position: Relationship of presenting part to maternal pelvis, i.e. ROP=right occiput posterior, or LOA=left occiput anterior.
• Presentation: Relationship between the leading fetal part and the pelvic inlet: cephalic, breech (complete, incomplete, frank or footling), face, brow, mentum or shoulder presentation.
• Lie: Relationship between the longitudinal axis of fetus and long axis of the uterus: longitudinal, oblique, and transverse.
• Caput or Caput succedaneum: oedema typically formed by the tissue overlying the fetal skull during the vaginal birthing process.

See also

• Childbirth
• List of obstetric topics
• Pelvic Bone Width
• Human pelvis
• Pregnancy
• Pubic symphysis
• Sacroiliac joint
• Sacrum

References

UpToDate Contents

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• 1. 正常な陣痛および分娩のメカニズム mechanism of normal labor and delivery
• 2. 正常分娩および遷延分娩、分娩停止 overview of normal labor and protraction and arrest disorders
• 3. 初回の出生前評価および妊娠初期の妊婦管理 initial prenatal assessment and first trimester prenatal care
• 4. 肩甲難産：リスクがある妊娠における危険因子および出産計画 shoulder dystocia risk factors and planning delivery of at risk pregnancies
• 5. 妊娠期乳癌：疫学および診断 gestational breast cancer epidemiology and diagnosis

English Journal

• Predicting women at risk for developing obstetric fistula: a fistula index? An observational study comparison of two cohorts.

• Browning A1, Lewis A, Whiteside S.Author information 1Selian Fistula Project, Arusha, Tanzania.AbstractOBJECTIVE: To ascertain if a predictor of obstructed labour and obstetric fistula (OF) occurrence could be devised.
• BJOG : an international journal of obstetrics and gynaecology.BJOG.2014 Jan 10. doi: 10.1111/1471-0528.12527. [Epub ahead of print]
• OBJECTIVE: To ascertain if a predictor of obstructed labour and obstetric fistula (OF) occurrence could be devised.DESIGN: Observational study of two cohorts.SETTING: Selian Lutheran Mission Hospital, Arusha, Tanzania and Aberdeen Women's Centre, Freetown, Sierra Leone.POPULATION: All women presenti
• PMID 24405643

• Prediction of cesarean delivery using the fetal-pelvic index.

• Macones GA1, Chang JJ, Stamilio DM, Odibo AO, Wang J, Cahill AG.Author information 1Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO. Electronic address: maconesg@wustl.edu.AbstractOBJECTIVE: The purpose of this study was to estimate the usefulness of the fetal-pelvic index (FPI) in the prediction of cesarean delivery among nulliparous and women who undergo a trial of labor after cesarean delivery (TOLAC).
• American journal of obstetrics and gynecology.Am J Obstet Gynecol.2013 Nov;209(5):431.e1-8. doi: 10.1016/j.ajog.2013.06.026. Epub 2013 Jun 19.
• OBJECTIVE: The purpose of this study was to estimate the usefulness of the fetal-pelvic index (FPI) in the prediction of cesarean delivery among nulliparous and women who undergo a trial of labor after cesarean delivery (TOLAC).STUDY DESIGN: This prospective cohort study included subjects at 2 hospi
• PMID 23791690

• Delivery for women with a previous cesarean: guidelines for clinical practice from the French College of Gynecologists and Obstetricians (CNGOF).

• Sentilhes L1, Vayssière C, Beucher G, Deneux-Tharaux C, Deruelle P, Diemunsch P, Gallot D, Haumonté JB, Heimann S, Kayem G, Lopez E, Parant O, Schmitz T, Sellier Y, Rozenberg P, d'Ercole C.Author information 1Service de Gynécologie-Obstétrique, CHU Angers, 49933 Angers, France. Electronic address: loicsentilhes@hotmail.com.AbstractThe primary cause of uterine scars is a previous cesarean. In women with a previous cesarean, the risks of maternal complications are rare and similar after a trial of labor after cesarean (TOLAC) and after an elective repeat cesarean delivery (ERCD), but the risk of uterine rupture is higher with TOLAC (level of evidence [LE]2). Maternal morbidity in women with previous cesareans is higher when TOLAC fails than when it leads to successful vaginal delivery (LE2). Although maternal morbidity increases progressively with the number of ERCD, maternal morbidity of TOLAC decreases with the number of successful previous TOLAC (LE2). The risk-benefit ratio considering the risks of short- and long-term maternal complications is favorable to TOLAC in most cases (LE3). Globally, neonatal complications are rare regardless of the mode of delivery for women with previous cesareans. The risks of fetal, perinatal, and neonatal mortality during TOLAC are low. Nonetheless, these risks are significantly higher than those associated with ERCD (LE2). The risks of mask ventilation, intubation for meconium-stained amniotic fluid, and neonatal sepsis all increase in TOLAC (LE2). The risk of transient respiratory distress increases in ERCD (LE2). To reduce this risk, and except in particular situations, ERCD must not be performed before 39 weeks (grade B). TOLAC is possible for women with a previous cesarean before 37 weeks, with 2 previous cesareans, with a uterine malformation, a low vertical incision or an unknown incision, with a myomectomy, postpartum fever, an interval of less than 6 months between the last cesarean delivery and the conception of the following pregnancy, if the obstetric conditions are favorable (professional consensus). ERCD is recommended in women with a scar in the uterine body (grade B) and a history of 3 or more cesareans (professional consensus). Ultrasound assessment of the risk of uterine rupture in women with uterine scars has not been shown to have any clinical utility and is therefore not recommended during pregnancy to help decide the mode of delivery (professional consensus). Use of X-ray pelvimetry to decide about TOLAC is associated with an increase in the repeat cesarean rate without any reduction in the rate of uterine rupture (LE2). It is unnecessary for deciding mode of delivery and for managing labor during TOLAC (grade C). TOLAC should be encouraged for women with a previous vaginal delivery either before or after the cesarean, a favorable Bishop score or spontaneous labor, and for preterm births (grade C). For women with a fetus with an estimated weight of more than 4500 g, especially in the absence of a previous vaginal delivery and those with supermorbid obesity (BMI>50), ERCD must be planned from the outset (grade C). For all of the other clinical situations envisioned (maternal age>35 years, diabetes, morbid obesity, prolonged pregnancy, breech presentation and twin pregnancy), TOLAC is possible but the available data do not allow specific guidelines about the choice of mode of delivery, in view of the low levels of proof (grade C). The decision about planned mode of delivery must be shared by the patient and her physician and made by the 8th month, taking into account the individual risk factors for TOLAC failure and uterine rupture (professional consensus). TOLAC is the preferred choice for women who do not have several risk factors (professional consensus). The availability onsite of an obstetrician and anesthetist must be pointed out to the patient. If the woman continues to prefer a repeat cesarean after adequate information and time to think about it, her preference should be honored (professional consensus). Labor should be induced in woman with a previous cesarean only for medical indications (professional consensus). Induction of labor increases the risk of uterine rupture, which can be estimated at 1% if oxytocin is used and 2% with vaginal prostaglandins (LE2). Mechanical methods of induction have not been studied sufficiently. Misoprostol appears to increase the risk of uterine rupture strongly (LE4). Based on the information now available, its use is not recommended (professional consensus). Routine use of internal tocodynamometry does not prevent uterine rupture (professional consensus). The increased risk of uterine rupture associated with oxytocin use is dose-dependent (LE3). In the active phase, it is recommended that the total duration of failure to progress should not exceed 3h; at that point, a cesarean should be performed (professional consensus). Epidural analgesia must be encouraged. The simple existence of a uterine scar is not an indication for a routine manual uterine examination after VBAC (grade C).
• European journal of obstetrics, gynecology, and reproductive biology.Eur J Obstet Gynecol Reprod Biol.2013 Sep;170(1):25-32. doi: 10.1016/j.ejogrb.2013.05.015. Epub 2013 Jun 28.
• The primary cause of uterine scars is a previous cesarean. In women with a previous cesarean, the risks of maternal complications are rare and similar after a trial of labor after cesarean (TOLAC) and after an elective repeat cesarean delivery (ERCD), but the risk of uterine rupture is higher with T
• PMID 23810846

Japanese Journal

• 現代の成熟期早期の女性の骨盤の形状とその関連因子，日常生活への影響

• 広島国際大学看護学ジャーナル 11(1), 13-25, 2014-03-31
• NAID 120005442105

• 術前画像診断と手術難易度評価 (特集 大腸癌の最新治療 : 治癒に向けた最先端研究) -- (臨床研究)

• 日本臨床 72(1), 77-81, 2014-01
• NAID 40019920564

• 受傷機転のない新生児頭蓋骨陥没骨折の1例

• 産婦人科の進歩 65(1), 95-99, 2013
• NAID 130003362659

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