PHYSIOLOGICAL CHANGES IN PREGNANCY AND OBSTETRIC EMERGENCIES Shankari Arulkumaran BSc MSc MD MRCOG Consultant Obstetrician and Gynaecologist St Mary s Hospital Imperial College NHS Trust
OVERVIEW Obstetric emergencies Shoulder dystocia Cord prolapse Maternal collapse Maternal collapse Cardiac disease Thromboembolism Pre-eclampsia/ Eclampsia Conclusion
PHYSIOLOGICAL CHANGES IN PREGNANCY
OBSTETRIC EMERGENCIES Maternal collapse Shoulder dystocia Cord prolapse
SHOULDER DYSTOCIA Difficulty in delivering the shoulder after the delivery of the head. Usually due the anterior shoulder being impacted against the symphysis pubis or the posterior shoulder being impacted against the sacral promontary. Incidence is 1:200. Associations: macrosomia, diabetes, prolonged labour, instrumental delivery. Management: McRoberts, episiotomy, internal manoeuvres, symphisotomy, Zavanelli s, cleidotomy. Consequences: Erb s palsy, fractured clavicle/ humerus, death.
CORD PROLAPSE
MATERNAL COLLAPSE Massive thromboembolism Haemorrhage Eclampsia Anaphylaxis Septic shock Cardiac disease
CARDIAC DISEASE AND HAEMODYNAMIC CHANGES
Sub-classification of cardiac deaths for whom information was available for an in -depth review, UK and Ireland, 2009 14 Ischaemic deaths 34 Atherosclerosis 16 Coronary artery dissection 11 Other 7 Valvular heart disease 11 Valve disease 9 Endocarditis Essential hypertension 6 Myocardial disease/ cardiomyopathy 27 Dilated cardiomyopathy 4 Left ventricular hypertrophy (LVH) with or without fibrosis 5 Obesity cardiomyopathy 2 Myocarditis 3 Peripartum cardiomyopathy 9 Defined cardiomyopathy Hypertrophic obstructive cardiomyopathy 1 Arrhythmogenic right ventricular cardiomyopathy 2 Ventricular disease (not otherwise specified) 1 Sudden arrhythmic cardiac deaths with a morphologically normal heart (SADS/MNH) 47 Aortic dissection 21 Others 7 Pulmonary arterial hypertension 6 Undetermined cardiovascular disease 1 TOTAL 153 Women with Congenital Heart Disease (CHD) (included in figures above) 11 Deaths from aortic dissection 5 Deaths from valvular heart disease 4 Deaths from pulmonary arterial hypertension 2
CARDIAC DISEASE A woman presented in the early third trimester with severe chest pain causing her to sit up in a chair for some of the night. The pain was consistently described as interscapular and she required repeated analgesia. Troponin and a VQ perfusion scan were normal and therefore since pulmonary embolism had been excluded she was discharged home. Approximately 36 hours after her discharge she collapsed at home with severe abdominal and chest pain. An ambulance was called and she was delivered by perimortem caesarean section in the Emergency Department. During her resuscitation which lasted over an hour she had thrombolysis, but no echocardiogram or a pericardiocentesis. Tamponade was not considered as a possible cause of her arrest. Postmortem examination showed a dissection of the ascending aorta and a haemopericardium.
CARDIOVASCULAR ADAPTATION Peripheral vasodilatation Mediated by endothelium dependent factors Upregulated by oestradiol and probably vasodilatory prostaglandins Peripheral vasodilatation leads to a fall in the systemic vascular resistance Cardiac output increases by 40% Achieved by an increase in stroke volume and by a lesser degree, heart rate
LABOUR ASSOCIATED CHANGES Further increases in cardiac output. Auto-transfusion of 300-500ml of blood back into the circulation. After delivery, CO increases by 60-80% followed by a rapid decline to prelabour values within approx. 1 hour of delivery. Transfer of fluid from the extravascular space increases venous return and stroke volume further.
NORMAL FINDINGS ON EXAMINATION Bounding/ collapsing pulse Ejection systolic murmur Loud first heart sound Third heart sound Relative sinus tachycardia Ectopic beats Peripheral oedema
NORMAL FINDINGS ON ECG Atrial and ventricular ectopics Q wave (small) and inverted T wave in lead III ST segment and T wave inversion in the inferior and lateral leads QRS axis leftward shift
THROMBOEMBOLISM AND COAGULATION CHANGES
THROMBOEMBOLISM A morbidly obese woman who gained a significant amount of weight during the pregnancy was prescribed an inadequate dose of low molecular weight heparin at the end of pregnancy when she became immobile. Following an elective caesarean delivery, she received the correct weightappropriate dose but upon discharge this was inadvertently halved. Furthermore she was only given a prescription to cover two weeks although it was intended that the GP prescribe another four weeks of prophylaxis.this did not happen. She contacted her GP a total of four times with leg pain before a referral to hospital as an outpatient was made. She collapsed en route to hospital, was thrombolysed but died a week later within a month of delivery.
CHANGES IN THE COAGULATION SYSTEM Changes in the coagulation system during pregnancy produce a physiological hypercoagulable state. The concentrations of certain clotting factors particularly VIII, IX and X are increased. Fibrinogen levels are increased by 50%. Fibrinolytic activity is also increased. Concentrations of endogenous anticoagulants such as anti-thrombin and protein S decrease.
PRE-ECLAMPSIA AND SYSTEMIC CHANGES
PRE-ECLAMPSIA A low risk woman had a normal blood pressure at booking but did not have her urinetested.shehadahighrisktestfordownssyndromeandwasreferredto fetal medicine. The fetus was small (3rd centile), and extensive fetal investigations were performed but no maternal checks. At 21 weeks she was found unresponsive with slurred speech, severe hypertension and 4+ proteinuria. She never regained consciousness and died from her intracranial bleed.
ECLAMPSIA A woman in her first pregnancy had repeated severe hypertension on home monitoring but had a normal blood pressure in clinic with no proteinuria. In the third trimester she developed proteinuria and a urine sample was sent to the laboratory for a protein-creatinine ratio. The result was not followed up and the woman was returned to midwifery care. Two weeks later she was found dead at home with signs of having had an eclamptic fit. Death was certified as due to eclampsia.
PET Commonest medical problem encountered in pregnancy. Pregnancy specific multisystem disorder with unpredictable, variable and widespread manifestations. Diffuse vascular endothelial dysfunction may cause widespread circulatory disturbances including the renal, hepatic, cardiovascular, central nervous and coagulation systems. It can be thought of as a 2 stage disorder: abnormal perfusion of the placenta and the maternal syndrome.
PHYSIOLOGICAL CHANGES Normal pregnancy is associated with a systemic inflammatory response and this is exacerbated in PET. There is an increased capillary permeability, an increase in pro-thrombotic factors, increased platelet activation and increased vascular tone. These factors cause widespread microvascular damage that leads to maternal manifestations such as hypertension, proteinuria and hepatic disturbances.
CONCLUSION The need to understand the basis of the normal physiological changes in pregnancy. The need for multi-disciplinary care.
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