Obstetrics by Ten Teachers

Louise C Kenny, Jenny E. Myers, Louise C. Kenny, Jenny E. Myers

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781498744478
• Edition: 20
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

First published in 1917 as 'Midwifery', Obstetrics by Ten Teachers is well established as a concise, yet comprehensive, guide within its field. The twentieth edition has been thoroughly updated by a new team of 'teachers', integrating clinical material with the latest scientific developments that underpin patient care. Each chapter is highly structured, with learning objectives, definitions, aetiology, clinical features, investigations, treatments, case histories and key point summaries and additional reading where appropriate. New themes for this edition include 'professionalism' and 'global health' and information specific to both areas is threaded throughout the text. Along with its companion Gynaecology by Ten Teachers the book will continue to provide an accessible 'one stop shop' in obstetrics and gynaecology for a new generation of doctors.

CHAPTER 1
Obstetric history and examination

LOUISE C KENNY AND JENNY E MYERS

Introduction

Obstetric history

Obstetric examination

Presentation skills

History template

Further reading

LEARNING OBJECTIVES

• To understand the principles of taking an obstetric history.
• To understand the key components of an obstetric examination.
• How to perform an appropriate obstetric examination.

Introduction

Taking a history and performing an obstetric examination are different compared with the history and examination in other specialities. The main difference is that the patient is normally a healthy woman undergoing a normal life event. Antenatal care is designed to support this normal physiological process and to detect early signs of complications. The type of questions asked during the history change with gestation, as does the purpose and nature of the examination. The history will often cover physiology, pathology and psychology and must always be sought with care and sensitivity.

Obstetric history

Introduction

When meeting a patient for the first time, always introduce yourself; tell the patient who you are and why you have come to see them. Make sure that the patient is seated comfortably. Some women will wish another person to be present, even just to take a history, and this wish should be respected.

The questions asked must be tailored to the purpose of the visit. At a booking visit, the history must be thorough and meticulously recorded. Once this baseline information is established, there is no need to go over this information at every visit. All women attend for routine antenatal visits (usually performed by the midwife or general practitioner [GP]) and occasionally women attend for a specific reason or because a complication has developed.

Some areas of the obstetric history cover subjects that are intensely private. In occasional cases there may be events recorded in the notes that are not known by other family members, such as previous terminations of pregnancy. It is vital to be aware of and sensitive to each individual situation.

Dating the pregnancy

Pregnancy has been historically dated from the last menstrual period (LMP), not the date of conception. The median duration of pregnancy is 280 days (40 weeks) and this gives the estimated date of delivery (EDD). This assumes that:

• The cycle length is 28 days.
• Ovulation occurs generally on the 14th day of the cycle.
• The cycle was a normal cycle (i.e. not straight after stopping the oral contraceptive pill or soon after a previous pregnancy).

The EDD is calculated by taking the date of the LMP, counting forward by 9 months and adding 7 days. If the cycle is longer than 28 days, add the difference between the cycle length and 28 to compensate.

In most antenatal clinics, there are pregnancy calculators (wheels) that do this for you (Figure 1.1). Pregnancy-calculating wheels do differ a little and may give dates that are a day or two different from those previously calculated. There is also an extensive range of pregnancy calculator Apps for smartphones available to download for free (Figure 1.2). However, almost all women who undergo antenatal care in the UK will have an ultrasound scan in the late first trimester or early second trimester. The purposes of this scan are to establish dates, to ensure that the pregnancy is ongoing and to determine the number of fetuses. If performed before 20 weeks, the ultrasound scan can be used for dating the pregnancy. After this time, the variability in growth rates of different fetuses makes it unsuitable for use in defining dates. It has been shown that ultrasound-defined dates are more accurate than those based on a certain LMP. This may be because the actual time of ovulation in any cycle is much less fixed than was previously thought. Therefore, the National Institute for Health and Care Excellence (NICE) guideline on Antenatal Care recommends that that pregnancy dates are set only by ultrasound using the crown–rump measurement between 10 weeks 0 days and 13 weeks 6 days, and the head circumference from 14 to 20 weeks. Regardless of the date of the LMP this EDD is used.

Figure 1.1 Gestation calendar wheel.

Figure 1.2 Gestation calendar App on a smartphone. (Courtesy of Dr Andrew Yu, Yale University.)

It is important to define the EDD at the booking visit, as accurate dating is important in later pregnancy for assessing fetal growth. In addition, accurate dating reduces the risk of premature elective deliveries, such as induction of labour for post-mature pregnancies and elective caesarean sections.

Social history

The social history requires considerable sensitivity, but it is a vitally important part of the obstetric history as social circumstances can have a dramatic influence on pregnancy outcome. The most recent report from the UK, Confidential Enquiries into Maternal Deaths and Morbidity (2009–12) echoes previous reports and details that maternal mortality is higher amongst older women, those living in the most deprived areas and amongst women from some ethnic minority groups. Importantly, one-third of women who experience domestic violence are hit for the first time while pregnant and women are known to be at higher risk of domestic abuse, leading to homicide when pregnant or postpartum. Women who are experiencing domestic abuse, may be at higher risk of abuse during pregnancy and of adverse pregnancy outcome, because they may be prevented from attending antenatal appointments, may be concerned that disclosure of their abuse may worsen their situation and be anxious about the reaction of health professionals.

Enquiring about domestic violence is extremely difficult. It is recommended that all women are seen on their own at least once during pregnancy, so that they can discuss this, if needed, away from an abusive partner. This is not always easy to accomplish. If you happen to be the person with whom this information is shared, you must ensure that it is passed on to the relevant team, as this may be the only opportunity the woman has to disclose it. Sometimes, younger women find medical students and young doctors much easier to talk to. Be aware of this.

Smoking, alcohol and drug intake also form part of the social history. Smoking causes a reduction in birthweight in a dose-dependent way. It also increases the risk of miscarriage, stillbirth and neonatal death. There are interventions that can be offered to women who are still smoking in pregnancy (see Chapter 3, Normal fetal development and growth and Chapter 6, Antenatal obstetric complications).

Complete abstinence from alcohol is advised, as the safety of alcohol is not proven. However, alcohol is probably not harmful in small amounts (less than one drink per day). Binge drinking is particularly harmful and can lead to a constellation of features in the baby known as fetal alcohol syndrome (see Chapter 3, Normal fetal development and growth and Chapter 6, Antenatal obstetric complications).

Enquiring about recreational drug taking is more difficult. Approximately 0.5–1% of women continue to take recreational drugs during pregnancy. Be careful not to make assumptions. During the booking visit, the midwife should enquire directly about drug taking. If it is seen as part of the long list of routine questions asked at this visit, it is perceived as less threatening. However, sometimes this information comes to light at other times. Cocaine and crack cocaine are the most harmful of the recreational drugs taken, but all have some effects on the pregnancy, and all have financial implications (see Chapter 6, Antenatal obstetric complications).

By the time you have finished your history and examination you should know the following facts that are important in the social history:

• Whether the patient is single or in a relationship and what sort of support she has at home.
• Generally whether there is a stable income coming into the house.
• What sort of housing the patient occupies (e.g. a flat with lots of stairs and no lift may be problematic).
• Whether the woman works and for how long she is planning to work during the pregnancy.
• Whether the woman smokes/drinks or uses drugs.
• If there are any other features that may be important.

Previous obstetric history

Past obstetric history is one of the most important areas for establishing risk in the current pregnancy. It...